How to Migrate from Mailchimp to Klaviyo: The Ultimate Step-by-Step 2026 Guide

If you're running an eCommerce brand on Mailchimp right now and you've been thinking about Klaviyo, you're not alone. We've migrated dozens of brands off Mailchimp (and Omnisend, Drip, HubSpot, and plenty of others) and the pattern is always the same: people know they should switch, they just don't want to deal with the migration.

And the urgency is real. Mailchimp laid off another round of employees in early 2026 as Intuit continues to restructure the platform. Features are being sunset, pricing is going up, and the eCommerce-specific roadmap looks thinner every quarter. We wrote about this in detail in our piece on the 2026 email marketing shakeout and Mailchimp layoffs. If you've been on the fence, the window to migrate cleanly is right now, before another round of changes hits.

A bad migration can tank your deliverability, lose historical data, and cost you weeks of revenue. But a well-planned one? You won't miss a single send.

This is the guide we wish existed when we started doing these. Every step, in order, with the specific screens you'll click through in both platforms. Whether you're doing this yourself or handing it off to an agency, this is what the full process looks like in 2026.

Why Brands Are Moving from Mailchimp to Klaviyo in 2026

Mailchimp and Klaviyo are fundamentally different tools at this point. Mailchimp started as a newsletter platform and has tried to bolt on eCommerce features over the years. Klaviyo was built from the ground up for eCommerce.

The biggest differences that actually matter:

• Shopify integration. Mailchimp removed their native Shopify integration back in 2019. They brought back a version of it, but it's still not the same as Klaviyo's real-time, native sync that pulls in orders, products, browsing behavior, and customer events automatically.
• Segmentation depth. Klaviyo lets you segment based on literally any event or property, including predicted behaviors like next order date, churn risk, and customer lifetime value. Mailchimp's segmentation is basic by comparison.
• Revenue attribution. Klaviyo ties every email and SMS directly to revenue at the campaign and flow level. You can see exactly how much money each automation is generating. Mailchimp's reporting is surface-level.
• SMS is built in. Klaviyo handles email and SMS in the same platform, same flows, same segments. With Mailchimp, SMS is a separate add-on that doesn't talk to your email data the way it should.
• Pricing at scale. Mailchimp gets expensive fast once you're past 10,000 contacts, especially with their recent pricing changes under Intuit. Klaviyo's pricing is more transparent and typically better value for brands doing real volume.

That said, Mailchimp is fine if you're a local business sending a monthly newsletter. But if you're an eCommerce brand doing $1M+ in revenue and relying on email and SMS to drive 25-40% of your top line, Klaviyo is the tool that was built for what you're trying to do.

Before You Touch Anything: The Pre-Migration Audit

This is where most DIY migrations go sideways. People jump straight into connecting accounts and start losing things they didn't realize they needed.

Before you do anything else, sit down and document your entire Mailchimp setup. Open a spreadsheet and go through each of these:

Subscriber Lists and Segments

In Mailchimp, go to Audience and note every audience you have. For each one, record:

• Total subscribed contacts
• Total unsubscribed contacts
• Total cleaned (bounced) contacts
• Any segments you've built and their criteria
• Any tags you're using to organize contacts

This is also the perfect time to clean your list. If someone hasn't opened an email in 12 months, they're dead weight. Don't pay to migrate contacts who will never buy from you. Export them separately and suppress them in Klaviyo from the start.

Active Automations

Go to Automations in Mailchimp and screenshot every active automation. For each one, write down:

• The trigger (what starts it)
• How many emails are in the sequence
• The timing between each email
• Any conditional logic or branching

Klaviyo calls these "flows" and you'll need to rebuild them from scratch. The integration doesn't carry automations over. Having this documented saves hours.

Signup Forms

List every signup form on your site. Pop-ups, embedded forms, footer forms, checkout opt-ins, landing page forms. Note which Mailchimp list each one feeds into and where it lives on your site. You'll need to replace all of these with Klaviyo forms.

Email Templates

If you have templates you want to keep, note which ones. Honestly though, this is usually a good time to start fresh. Klaviyo's template builder is significantly better than Mailchimp's, and most brands' Mailchimp templates aren't mobile-optimized the way they should be.

DNS and Authentication

Log into wherever your domain DNS is managed (GoDaddy, Cloudflare, Namecheap, etc.) and screenshot your current email authentication records: SPF, DKIM, and DMARC. You'll need to add new records for Klaviyo and eventually remove the Mailchimp ones.

Third-Party Integrations

Check what other tools are connected to Mailchimp. Common ones include Shopify, WooCommerce, WordPress, Zapier, review platforms, loyalty programs, etc. You'll need to reconnect these to Klaviyo instead.

Step 1: Create Your Klaviyo Account and Connect Your Store

Go to klaviyo.com and create your account. Klaviyo offers a free plan for up to 250 contacts with 500 email sends per month, so you can set everything up before you start paying.

The very first thing you should do, before connecting Mailchimp, is connect your eCommerce platform. If you're on Shopify (which most of the brands we work with are), this is dead simple:

1. In Klaviyo, go to Settings > Integrations
2. Search for Shopify and click Add Integration
3. Enter your Shopify store URL (your myshopify.com domain)
4. Authorize the connection in Shopify

Once connected, Klaviyo will start syncing your customer data, order history, product catalog, and browsing events in real time. This is already more data than Mailchimp ever had access to.

Important: If Mailchimp is still connected to Shopify, don't disconnect it yet. You'll do that at the end. But be aware that both platforms will be receiving data simultaneously during the migration period, which is fine and expected.

Step 2: Generate a Mailchimp API Key

Klaviyo has a built-in Mailchimp integration that pulls your contact data, engagement history, and campaign metrics directly. To use it, you need a Mailchimp API key.

In Mailchimp:

1. Click your profile icon in the bottom-left corner
2. Go to Account & billing
3. Click the Extras dropdown and select API keys
4. Click Create a Key
5. Name it something like "Klaviyo Migration" so you know what it's for
6. Click Generate Key
7. Copy the key immediately and save it somewhere secure. You can only see it once.

A quick note on security: this API key gives full access to your Mailchimp account. Don't share it publicly, don't put it in a Slack channel, and revoke it once the migration is complete.

Step 3: Connect Mailchimp to Klaviyo

Now back in Klaviyo:

1. Go to Settings > Integrations
2. Click Add Integration and search for Mailchimp
3. Click Install
4. Paste your Mailchimp API key in the field
5. Before clicking connect, review the Advanced options:
   • Collect open and click data for Mailchimp campaigns - check this. It syncs your historical engagement data so Klaviyo knows who's active and who isn't.
   • Create Klaviyo lists from Mailchimp audiences - check this. It mirrors your Mailchimp audience structure in Klaviyo.
   • Only sync contacts from specific audiences - use this if you have multiple audiences and only want to bring certain ones over. Otherwise leave it unchecked to sync everything.
6. Click Connect to Mailchimp

Data will start syncing within a few minutes. The initial historical sync pulls all contacts and the last 90 days of campaign data. After that, existing audiences sync every 30 minutes, and new audiences or campaigns sync every 6 hours.

What Gets Synced (and What Doesn't)

The Mailchimp integration will automatically sync:

• All contact profiles (names, emails, locations)
• Subscription status (subscribed, unsubscribed, cleaned)
• Mailchimp audience ratings
• Campaign engagement data (opens, clicks, receives) for the last 90 days

What does NOT sync automatically:

• Tags - you'll need to export and import these manually (covered in Step 4)
• Automations/journeys - these need to be rebuilt as Klaviyo flows (Step 6)
• Email templates - these need to be exported and imported (Step 5)
• Signup forms - these need to be recreated (Step 7)
• Custom merge fields beyond the basics - check your Mailchimp merge fields and make sure the important ones came through as Klaviyo profile properties

Step 4: Export and Import Your Mailchimp Tags

If you use tags in Mailchimp to organize your contacts (VIP customers, product interest groups, source tracking, etc.), these won't come over through the integration. You need to export them manually.

In Mailchimp:

1. Go to Audience > Manage contacts > Tags
2. For each tag you want to migrate, click the dropdown next to View
3. Select Export as CSV
4. Save the CSV file

In Klaviyo:

1. Go to Audience > Lists & Segments
2. You can either create a new list for each tag group, or import the CSVs with a custom property that preserves the tag information
3. Click Import Contacts and upload each CSV
4. Map the columns to Klaviyo profile properties
5. Add a custom property like "mailchimp_tag" with the tag name as the value

Once imported, you can build Klaviyo segments based on these custom properties, which is actually more powerful than how tags work in Mailchimp anyway.

Step 5: Migrate Your Email Templates

You have two options here, and honestly, we almost always recommend option one.

Option A: Rebuild in Klaviyo (Recommended)

Klaviyo's drag-and-drop email builder is significantly more advanced than Mailchimp's. It supports dynamic content blocks, product feeds, conditional visibility, and mobile-specific layouts out of the box. Most brands find that rebuilding their templates in Klaviyo produces better-looking, more functional emails than what they had before.

Klaviyo also has a template library with pre-built designs optimized for eCommerce. You can use these as starting points and customize them to match your brand.

This is the approach we take for every Klaviyo migration service. We don't just copy what you had. We rebuild it better.

Option B: Export HTML from Mailchimp

If you have custom templates you absolutely need to preserve:

1. In Mailchimp, go to Campaigns > Email templates
2. Find the template you want to export
3. Click the dropdown next to the template name and select Export as HTML
4. Confirm the export and save the HTML file

Before importing into Klaviyo, you need to swap out Mailchimp's template tags for Klaviyo's format:

• *|FNAME|* becomes {{ first_name }}
• *|LNAME|* becomes {{ last_name }}
• *|EMAIL|* becomes {{ email }}
• *|UNSUB|* becomes {% unsubscribe %} (this one is required in every Klaviyo template)
• *|LIST:COMPANY|* becomes {{ organization.name }}
• *|LIST:ADDRESS|* becomes {{ organization.address }}

Open the HTML file in any text editor (VS Code, Sublime Text, even Notepad), do a find-and-replace for each tag, then:

1. In Klaviyo, go to Content > Templates
2. Click Create Template > Import Template
3. Upload your edited HTML file
4. Review it in the editor to make sure everything looks right

Fair warning: imported HTML templates won't be editable in Klaviyo's drag-and-drop builder. You'll need to edit them in HTML mode. This is another reason we usually recommend just rebuilding.

Step 6: Rebuild Your Automations as Klaviyo Flows

This is the most time-consuming part of the migration, and it's also where the biggest improvements happen. Mailchimp's "customer journeys" are limited compared to what Klaviyo flows can do.

If you're doing this yourself, start with the flows that drive the most revenue:

Priority 1: Welcome Series

Trigger: Someone subscribes to your list. Typically 3-5 emails introducing your brand, building trust, and driving the first purchase. In Klaviyo, you can split this flow based on whether someone has purchased before, what product they were looking at, and even their predicted value.

Priority 2: Abandoned Cart / Abandoned Checkout

Trigger: Someone adds to cart or starts checkout but doesn't complete. This is usually the single highest-revenue flow for eCommerce brands. Klaviyo's version can include dynamic product blocks showing exactly what was left behind, plus cross-sell recommendations.

Priority 3: Post-Purchase

Trigger: Someone completes an order. Thank them, set delivery expectations, ask for a review, then cross-sell related products. Klaviyo lets you split this based on first-time vs. repeat buyer, order value, and specific products purchased.

Priority 4: Browse Abandonment

Trigger: Someone views a product but doesn't add to cart. This one doesn't exist in most Mailchimp setups because Mailchimp doesn't have the behavioral tracking depth. It's one of the biggest revenue unlocks when moving to Klaviyo.

Priority 5: Winback

Trigger: A customer hasn't purchased in X days (typically 60-120, depending on your product cycle). Klaviyo can use predictive analytics to trigger this based on each customer's individual expected next order date, rather than a blanket time window.

Klaviyo has a flow library with pre-built templates for all of these, plus sunset flows, back-in-stock alerts, price drop notifications, VIP tiers, review requests, and more. You don't need to build from a blank canvas.

For brands with complex automation logic, this is typically where it makes sense to hire an agency to migrate your Mailchimp to Klaviyo. We've seen DIY migrations where someone spends weeks rebuilding 15+ flows, only to find half of them have logic errors that aren't caught for months.

Step 7: Recreate Your Signup Forms

Mailchimp signup forms don't transfer to Klaviyo. Every form on your site that feeds into Mailchimp needs to be replaced.

In Klaviyo, go to Signup Forms and create new forms for:

• Pop-up forms - Klaviyo's form builder handles exit-intent, timed, scroll-based, and page-specific targeting natively
• Embedded forms - for your footer, sidebar, or inline positions
• Flyout forms - less intrusive alternative to pop-ups

Klaviyo forms default to double opt-in, which means new subscribers get a confirmation email before they're added to your list. This is better for deliverability but can reduce conversion rates on your forms. You can switch to single opt-in in your list settings if you prefer, though we generally recommend keeping double opt-in for new accounts.

If you're using a third-party form tool like Justuno, Privy, or Alia, you just need to update the integration to point to Klaviyo instead of Mailchimp. Most of these tools have native Klaviyo integrations.

Don't forget: embedded forms in blog posts, landing pages, and checkout. These are the ones people miss most often.

Step 8: Set Up Email Authentication and Warm Your Domain

This step is critical and it's the one most likely to go wrong in a DIY migration. If you skip domain warm-up, your deliverability will tank and it can take weeks to recover.

Email Authentication

In Klaviyo, go to Settings > Email > Domains and add your sending domain. Klaviyo will give you DNS records to add:

• DKIM - two CNAME records that verify your emails are actually from you
• SPF - usually handled automatically if you're using Klaviyo's shared sending infrastructure, but required if you're on a dedicated sending domain

If you already have DMARC set up (and you should), make sure your DMARC policy accounts for Klaviyo as an authorized sender. A misconfigured DMARC record with a strict policy can cause Klaviyo emails to fail authentication entirely.

Domain Warm-Up

When you start sending from Klaviyo, mailbox providers (Gmail, Yahoo, Outlook) don't know you yet. Even if you had great deliverability on Mailchimp, that reputation doesn't transfer. You're starting fresh.

The warm-up process:

1. Week 1: Send only to your most engaged segment (opened or clicked in the last 30 days). Start with small volumes, maybe 1,000-5,000 per send.
2. Week 2: Expand to 60-day engaged. Double your volume.
3. Week 3: Expand to 90-day engaged. Continue ramping up.
4. Week 4: You should be close to full volume by now. Monitor your open rates, bounce rates, and spam complaint rates at each stage.

If at any point you see open rates drop significantly or spam complaints spike, slow down. Send to smaller, more engaged segments until things stabilize.

During the warm-up period, you might run campaigns from both Mailchimp (to your less engaged segments) and Klaviyo (to your engaged segments). This keeps revenue flowing while Klaviyo's reputation builds. Just make sure you're suppressing the Klaviyo-targeted contacts from your Mailchimp sends to avoid double-emailing.

Step 9: Test Everything Before Going Live

Before you fully cut over to Klaviyo, run through this checklist:

• Signup forms: Submit a test email to every form on your site. Check that it appears in the correct Klaviyo list.
• Welcome flow: Verify that the welcome series triggers when someone signs up.
• Abandoned cart: Add something to your cart, leave, and confirm the flow triggers.
• Browse abandonment: View a product and confirm the flow triggers (check the timing delay).
• Post-purchase: Place a test order and verify the flow triggers.
• Unsubscribe: Click the unsubscribe link in a test email and confirm the contact is properly suppressed.
• Dynamic content: Check that product blocks, name personalization, and conditional content all render correctly.
• Mobile rendering: Open every template on a phone. Seriously. Over 60% of email opens are on mobile.

This is not optional. We've seen brands go live with flows that had broken product blocks, wrong time delays, or missing unsubscribe links. Test each one individually.

Step 10: Sunset Mailchimp

Once everything is running smoothly in Klaviyo (give it at least a full week of sends with no issues), it's time to shut down Mailchimp.

1. Pause all Mailchimp automations. Go to each active automation and click Pause and Edit, then Pause. This prevents any double-sends.
2. Disconnect Mailchimp from Shopify (if applicable). In Shopify, go to Settings > Apps and sales channels and remove the Mailchimp connection.
3. Remove the Mailchimp integration from Klaviyo. Go to Settings > Integrations, click the action menu next to Mailchimp, and select Remove Integration. You only need to do this once all your data is synced and verified.
4. Remove Mailchimp tracking code from your website if you had it installed.
5. Revoke the API key you created for the migration. In Mailchimp, go to Account > Extras > API keys, find the key, and click Revoke.
6. Downgrade or cancel your Mailchimp plan. Don't delete your account immediately. Keep it on the free tier for a month or two in case you need to reference old campaigns or pull additional data.

Congratulations. You're on Klaviyo.

Common Mistakes That Tank Migrations

We've cleaned up enough botched migrations to have a pretty clear list of what goes wrong:

• Skipping domain warm-up. This is the number one killer. Brands switch to Klaviyo and immediately blast their full list. Gmail and Yahoo don't recognize you yet, your emails go to spam, your open rates crater, and it takes 4-6 weeks of careful rehabilitation to recover. Don't do this.
• Not suppressing Mailchimp bounces. If a contact was "cleaned" (bounced) in Mailchimp and already existed in Klaviyo as an active profile, the integration might not suppress them. Export your cleaned contacts from Mailchimp and upload them to Klaviyo's suppression list manually.
• Forgetting about transactional emails. If Mailchimp was handling any transactional emails (order confirmations, shipping notifications), make sure those are now handled by Shopify, Klaviyo, or another system before you shut Mailchimp down.
• Not updating third-party integrations. If you had Zapier zaps, review platform triggers, or loyalty program connections pointing to Mailchimp, they'll break when you deactivate your account. Update them to point to Klaviyo.
• Losing consent records. If you're subject to GDPR, make sure your consent timestamps and opt-in sources transfer properly. Klaviyo preserves subscription status from the Mailchimp sync, but you should verify that consent records are intact for compliance.
• Going live on a Friday. If something breaks, you want to catch it quickly. Launch mid-week when your team is around to monitor.

How Long Does This Actually Take?

For a typical eCommerce brand with 10,000-50,000 contacts, 5-10 active automations, and a standard set of templates:

• DIY migration: 3-6 weeks if you're thorough, potentially longer if you're learning Klaviyo for the first time
• With an experienced agency: 2-4 weeks, including domain warm-up

The calendar time is mostly driven by domain warm-up, which you can't rush without risking deliverability. The actual setup work (connecting platforms, rebuilding flows, creating forms) usually takes 1-2 weeks of focused work.

If you have a complex setup with 20+ flows, multiple audiences, heavy segmentation, and custom integrations, budget more time. We've done migrations that took 6 weeks for brands with genuinely complex email programs, and that's not a red flag. It just means there was a lot to get right.

If you'd rather hand this off to a team that's done it dozens of times with zero revenue disruption, our Mailchimp to Klaviyo migration service handles the entire process.

Frequently Asked Questions

Will I lose my email list if I switch from Mailchimp to Klaviyo?

No. The Klaviyo-Mailchimp integration syncs all your contacts, including their subscription status and engagement history. Unsubscribed and bounced contacts are automatically suppressed in Klaviyo. Your list data is preserved.

Can I run both Mailchimp and Klaviyo at the same time during migration?

Yes, and you should. Running both platforms in parallel during domain warm-up is the safest approach. Send to your most engaged contacts from Klaviyo while continuing to send to the rest from Mailchimp. Just make sure you're suppressing overlap so nobody gets the same email twice.

How much does it cost to switch from Mailchimp to Klaviyo?

Klaviyo is free for up to 250 contacts. Beyond that, pricing is based on your contact count. For 10,000 contacts, expect to pay roughly $150/month for email only, or $210/month for email + SMS. Mailchimp's equivalent plan at 10,000 contacts runs about $100-175/month depending on features, so the costs are comparable. The ROI difference comes from Klaviyo's superior segmentation and automation driving more revenue per send.

Will my deliverability be affected by the switch?

It can be if you don't warm up properly. Your sending reputation doesn't transfer between platforms. Follow the domain warm-up process outlined above (start with engaged segments, gradually increase volume over 2-4 weeks) and you should be fine. If you skip this, you will almost certainly see deliverability problems.

Do I need to redesign all my emails?

You don't have to, but it's a great opportunity. You can import your existing Mailchimp templates as HTML, but they won't be editable in Klaviyo's drag-and-drop builder. Most brands use the migration as a chance to upgrade their email design, and Klaviyo's builder makes it pretty easy to create professional templates.

What about my Mailchimp automations? Do they transfer?

No. Automations (called "flows" in Klaviyo) need to be rebuilt. The good news is Klaviyo has a pre-built flow library with templates for every common eCommerce automation, and Klaviyo's flow builder is significantly more powerful than Mailchimp's customer journeys. Think of it as an upgrade, not just a recreation.

How long should I keep my Mailchimp account after migrating?

Keep it on the free tier for at least 2-3 months after migration. You might need to reference old campaigns, pull additional data, or check historical metrics. Once you're fully settled in Klaviyo and confident everything is running well, you can close it for good.

Can I migrate my Mailchimp data without the API integration?

Yes, but it's more manual. You can export your contacts as a CSV from Mailchimp (Audience > Export Audience) and import them directly into Klaviyo. The downside is you won't get engagement history (opens, clicks) transferred this way, which means Klaviyo won't know who your engaged vs. disengaged subscribers are. The API integration is the better path for eCommerce brands.

Sources

• Klaviyo Help Center: Migrate from Mailchimp to Klaviyo
• Mailchimp Help Center: View or Export Your Contacts
• Mailchimp Help Center: About API Keys
• EmailToolTester: Migrating from Mailchimp to Klaviyo - A Step-by-Step Guide (2025)
• Enchant Agency: Mailchimp to Klaviyo Migration - Complete 7-Step Guide
• Venturestream: Migrating from Mailchimp to Klaviyo - Everything You Need to Know