How to Migrate from Mailchimp to Klaviyo Without Missing a Send
Step-by-step Mailchimp to Klaviyo migration: what moves automatically, what to rebuild, SMS consent and warm-up, with a real 9-day example.
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To migrate from Mailchimp to Klaviyo, clean your list, connect Klaviyo's built-in Mailchimp integration, and carry every unsubscribe and bounce over to suppression. Then import SMS subscribers with their consent records, rebuild automations as Klaviyo flows, and warm up sending while both platforms run in parallel. This guide walks through each step, with a real example: a 250,000-contact store that moved in 9 days with every send on time.
What moves from Mailchimp to Klaviyo automatically, and what doesn't?
Klaviyo's built-in Mailchimp integration creates Klaviyo lists from your Mailchimp audiences and syncs standard contact details: names, email addresses, Mailchimp ratings and locations. Tags, custom fields, automations, drag-and-drop templates and sign-up forms don't move automatically. You export them or rebuild them in Klaviyo.
| What you have in Mailchimp | How it moves to Klaviyo |
|---|---|
| Audiences and contacts | Klaviyo's Mailchimp integration creates Klaviyo lists and syncs names, email addresses, Mailchimp ratings and locations |
| Tags and custom fields | Don't sync. Export from Mailchimp and import into Klaviyo as custom properties |
| Unsubscribes, bounces and complaints | Must end up on Klaviyo's suppression list. Export and upload anything the integration doesn't carry over |
| Custom-coded HTML templates | Export the HTML, swap Mailchimp's merge tags for Klaviyo's, and import |
| Drag-and-drop templates | Mailchimp can't export them. Rebuild in Klaviyo's template builder |
| Automations | Don't transfer. Rebuild as Klaviyo flows |
| Sign-up forms | Don't transfer. Rebuild in Klaviyo |
| SMS subscribers | Import with documented consent and original opt-in dates |
| Revenue tracking | Comes from Klaviyo's Shopify integration, which ties each email and text to the orders it earns |
Source: Klaviyo's guide to migrating from Mailchimp, checked November 2026.
How do I export all data from Mailchimp?
Use Mailchimp's account export. It bundles your audiences, templates, marketing emails and SMS data into a single ZIP file, which you download from the Manage my data page. Large accounts can take up to 24 hours. Only account Managers, Admins and Owners can run it, and deleted audiences can't be exported.
There are two ways to export, and a migration usually needs both:
| Export | What you get | Use it for |
|---|---|---|
| Full account export (Account, then Manage my data) | One ZIP with audiences, templates, marketing emails, SMS data and reports. Contacts come in separate files: subscribed, unsubscribed, cleaned and non-subscribed | A complete backup before you cancel Mailchimp |
| Audience export (Audience, then Export audience) | A ZIP of CSVs for one audience, segment, tag or group, split by contact status, with a separate SMS folder if you have SMS contacts | Importing contacts, tags and suppressions into Klaviyo |
Sources: Mailchimp's help center on exporting account data and exporting contacts, checked November 2026.
Run the full export before you cancel. Mailchimp notes that exported data can be re-imported, except email and SMS reports, so save the reports for your records. The unsubscribed and cleaned files are what you upload to Klaviyo's suppression list.
How do you migrate from Mailchimp to Klaviyo, step by step?
Work through six phases: plan, clean, import, rebuild, run both platforms in parallel while warming up, then cut over. Set your deadline from the Mailchimp renewal date, and don't switch Mailchimp off until Klaviyo is sending to your full list with healthy bounce, spam and unsubscribe rates.
1. Plan
- List every audience, tag, custom field, automation, template and sign-up form in Mailchimp.
- Check where SMS consent records live and what they include.
- Note your Mailchimp renewal date. That's your deadline.
2. Clean the list
- Remove unsubscribes, bounces and spam complaints from active sending.
- Decide what to do with contacts who haven't engaged in a long time, before you import them.
3. Import into Klaviyo
- In Klaviyo, open the Integrations tab, add the Mailchimp integration, and choose to create Klaviyo lists from your Mailchimp audiences.
- Export tags and custom fields from Mailchimp and import them as custom properties.
- Upload any suppressions the integration didn't carry over.
- Import SMS subscribers with their original opt-in dates.
- Connect Klaviyo to Shopify, so browsing and order events start flowing.
4. Rebuild
- Rebuild automations as Klaviyo flows. Start with abandoned cart and welcome.
- Import custom HTML templates after swapping merge tags (for example, Mailchimp's
*|FNAME|*becomes Klaviyo's{{ first_name }}), and include Klaviyo's unsubscribe tag. Rebuild drag-and-drop templates. - Rebuild sign-up forms and point them at Klaviyo lists.
5. Run both platforms in parallel and warm up
- Split the audience so each contact gets each send from only one platform.
- Move a growing share of sends to Klaviyo, and only step up when health metrics are healthy.
6. Cut over
- Send to the full list from Klaviyo.
- Pause every Mailchimp automation, so nobody gets emails twice.
- Remove the Mailchimp integration from Klaviyo, as Klaviyo recommends, and cancel Mailchimp before renewal.
How do you migrate without missing a send?
Run both platforms in parallel and split the audience, so every contact gets each send from only one platform. Move sending to Klaviyo in steps, and switch Mailchimp off only when Klaviyo reaches the full list. For Vertigo Vinyl, a drop-based record store, drops never stopped and nobody got the same email twice.
Vertigo Vinyl: share of list sent from Klaviyo
Source: Solo Media Group account team, October 2026.
Every Vertigo Vinyl drop sells out, so a missed send means lost sales. The move also had a hard deadline: everything had to be off Mailchimp before its renewal date. We split the audience between the platforms and moved more of it to Klaviyo at each step: 5%, 10%, 25%, 50%, then 100% by day 9. A step moved forward only when every health metric was healthy, and Mailchimp was turned off before the renewal.
Source: Solo Media Group account team, October 2026 migration. "9 days" counts from the first Klaviyo send to the full list.
How long does a Mailchimp to Klaviyo migration take?
It depends on list size, how many automations need rebuilding, and whether SMS is involved. The sending ramp itself can be quick when the list is clean: Vertigo Vinyl went from its first Klaviyo send to its full list of about 250,000 contacts in 9 days. Planning, cleaning and rebuilding come before that.
Work backward from your Mailchimp renewal date. Leave time for planning and rebuilding flows before the first Klaviyo send, then for a step-by-step ramp that can pause if a health metric rises.
How do you protect deliverability when you switch to Klaviyo?
Clean the list before importing, start with engaged contacts, and increase volume gradually, a process often called IP warming. Klaviyo itself recommends importing clean lists and sending to an engaged audience from the first send. Watch bounce, spam and unsubscribe rates at every step, and pause if any rises.
Vertigo Vinyl's three health metrics during the ramp, against the warning lines we watch:
| Health metric | Vertigo Vinyl | Warning line | Margin |
|---|---|---|---|
| Bounce rate | 0.14% | 1% | 7x below |
| Spam complaints | 0.002% | 0.1% | 50x below |
| Unsubscribes | 0.03% | 0.3% | 10x below |
The 0.1% spam line matches Google's guidance for bulk senders, which also asks senders never to reach 0.3%. Klaviyo's own migration checklist warns that importing unclean lists puts deliverability at risk.
Source for Vertigo Vinyl figures: Solo Media Group account team, October 2026 migration.
How do you move SMS subscribers from Mailchimp to Klaviyo?
Consent first. Move SMS subscribers with their original opt-in dates and records, and don't text anyone without documented consent. If your sending number changes, send one short message from the new number so subscribers recognize it. Vertigo Vinyl's SMS moved in one day, with 93% of first texts delivered.
Vertigo Vinyl had about 16,000 SMS contacts with mixed consent history. Every SMS opt-out moved with its status, and subscribers migrated with their original opt-in dates. After the switch to a new Klaviyo number, 0.9% unsubscribed.
Source: Solo Media Group account team, October 2026 migration. Klaviyo's migration checklist links to its resources for importing SMS contacts. Check your consent records and local rules before any import.
What happens to your flows, templates and forms?
They're rebuilt in Klaviyo, which is usually an upgrade. Mailchimp automations don't transfer, so rebuild them as Klaviyo flows triggered by Shopify events, such as viewed products, started checkouts and placed orders. Custom HTML templates can be imported; drag-and-drop templates and sign-up forms are rebuilt.
A migration is the right moment to fix what wasn't working. When we moved Lifelines to Klaviyo from its previous provider, we migrated every flow, form and campaign, updated the sign-up form to capture SMS, and launched SMS from zero. Lifelines then grew from one basic welcome flow to 11+ live automations in four months.
Revenue tracking improves too. Vertigo Vinyl's Mailchimp revenue tracking had broken after a site migration. On Klaviyo, every drop's email revenue is tracked again.
For which flows to build first, see our guide to Klaviyo email marketing for Shopify.
Should you clean your list before migrating?
Yes. Unengaged and invalid contacts hurt deliverability on a new platform, and Klaviyo bills on active profiles, so every unreachable contact you import costs money. Remove unsubscribes, bounces and spam complaints from active sending, and decide what to do with long-unengaged contacts before you import.
Klaviyo has billed on active profiles since its February 2025 billing change. Suppressed and unsubscribed profiles don't count toward the bill. Vertigo Vinyl's migration removed about 70,000 unreachable contacts from its roughly 250,000, so its list is smaller, healthier and cheaper.
Is Klaviyo better than Mailchimp for Shopify?
For most Shopify brands where email drives sales, yes. Klaviyo syncs Shopify browsing and order data, triggers flows on what shoppers do, and reports revenue per email. Mailchimp prices plans by contacts and monthly sends, while Klaviyo bills on active profiles. For a small list with simple newsletters, Mailchimp can still be enough.
Mailchimp's help center notes its plans are priced by the number of contacts and monthly email sends. We build Klaviyo programs for a living, so weigh our view with that in mind.
Should you migrate yourself or hire help?
A small list with a few simple automations is manageable in-house using Klaviyo's integration and this guide. Hire help when a missed send costs real money, when you have SMS subscribers to move, when you have many automations to rebuild, or when your revenue tracking is already broken.
Our Klaviyo email and SMS marketing team handles the full migration: planning, cleaning, consent-first SMS, flow rebuilds and a health-gated warm-up. Many clients keep us on afterward, as Vertigo Vinyl did.
Frequently asked questions
Is Klaviyo similar to Mailchimp?
Both send email and SMS, but they're built differently. Klaviyo is built around ecommerce data: it syncs Shopify browsing and order events, triggers flows on what shoppers do, and reports revenue per email. Mailchimp prices plans by contacts and monthly email sends; Klaviyo bills on active profiles.
Can you import Mailchimp templates into Klaviyo?
Only custom-coded ones. You can export a custom HTML template from Mailchimp and import it into Klaviyo, after swapping Mailchimp's merge tags for Klaviyo's. Mailchimp doesn't export drag-and-drop templates, so those are rebuilt in Klaviyo's template builder.
Do Mailchimp automations transfer to Klaviyo?
No. Automations have to be rebuilt as Klaviyo flows. That's usually an upgrade, because Klaviyo flows can trigger on Shopify events like viewed products, started checkouts and placed orders.
Do Mailchimp tags and custom fields transfer to Klaviyo?
Not automatically. Klaviyo's Mailchimp integration syncs standard contact details, such as names, email addresses, Mailchimp ratings and locations. Tags and custom audience fields are exported from Mailchimp and imported into Klaviyo as custom properties.
Will I lose subscribers when I move from Mailchimp to Klaviyo?
You shouldn't lose anyone you can legitimately reach. Every unsubscribe and bounce should move to Klaviyo's suppression list, and SMS subscribers should move with their original opt-in dates. When Vertigo Vinyl's SMS moved to a new number, 0.9% of subscribers unsubscribed after the change.
Can I keep Mailchimp running during the migration?
Yes, and you should. Run both platforms in parallel and split the audience, so each contact gets every send from only one platform. Switch Mailchimp off once Klaviyo is sending to the full list.
When should a Shopify brand switch from Mailchimp to Klaviyo?
When email is a real sales channel and you need flows triggered by shopping behavior, revenue attribution per email, or segments built on purchase history. Plan the move before your Mailchimp renewal date, so you don't pay for both longer than you need to.
How much does it cost to have a Mailchimp to Klaviyo migration done for you?
It depends on list size, SMS, the number of automations and template work. Solo Media Group quotes migrations per project as line items, after a free planning audit. You pay Klaviyo directly for the software.
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