A Mailchimp to Klaviyo migration for a Shopify store is not an export and import. Your subscribers move, but their consent history, suppression status, and the flows that earn most of your email revenue do not move on their own. The safe order is: connect Shopify to Klaviyo first, import contacts with their consent and suppression status intact, rebuild flows natively, run both platforms in parallel for a short window, then warm up sending before your first big campaign.
We run these migrations as part of our Klaviyo work, and the same five things go wrong every time someone treats it as a data transfer. The same applies if you are leaving Attentive, Omnisend, or Shopify Email.
1. Consent status gets flattened
Every contact in your old platform has a status: subscribed, unsubscribed, bounced, marked as spam, or cleaned. A careless export takes only the subscribed list, or worse, takes everyone and imports them as subscribed.
Both are expensive. Import only the subscribed list and you lose the record of who opted out, so a later import or integration can quietly re-add them. Import everyone as subscribed and you will email people who asked you not to, which damages your sender reputation and exposes you legally.
The fix: export each status separately. Import subscribers as subscribed and import everyone else into Klaviyo's suppression list, so they can never be emailed by accident.
2. SMS consent does not travel cleanly
SMS is stricter than email. For every SMS subscriber you migrate, keep the original consent timestamp and the source where they opted in. If you cannot document how someone gave consent to receive texts, do not text them from the new platform.
State rules are also changing. Our note on the Texas SMS compliance update covers one recent example. Check your terms, privacy policy, and opt-in language as part of the move rather than after it.
3. Flows do not migrate at all
This is the one that surprises people. Automations built in Mailchimp or Attentive cannot be imported into Klaviyo. They have to be rebuilt.
That is also the opportunity. Klaviyo's flows can branch on Shopify data (what someone browsed, bought, and how often), so a rebuild is the moment to replace a generic welcome series with one that splits purchasers from non-purchasers, and to add the flows you never had. Our guide to the Klaviyo flows every Shopify Plus brand needs lists what to build and in what order.
4. Two platforms send at once
During a migration it is easy to end up with two systems both reacting to the same Shopify event. The customer who abandons a cart gets two reminder emails with two different discount codes. Order confirmations can double up the same way.
The fix: build the Klaviyo flows in draft, switch each one live only as you turn off its equivalent in the old platform, and remove the old platform's Shopify app and signup forms on a planned date. Keep a short parallel window where the old platform sends nothing automated but still exists, so you can compare.
5. Sending reputation starts cold
Mailbox providers judge a sender partly by history. When you start sending from a new platform, especially with a new branded sending domain, you are building that history again. Blasting your full list on day one is the fastest way to land in spam.
The fix: set up domain authentication before the first send, then start with your most engaged subscribers (people who opened or clicked recently) and widen the audience over the following weeks. Do not schedule the migration right before Black Friday or a major launch.
The order we run it in
- Audit the old platform. List every flow, form, segment, and integration, and note what each one earns.
- Connect Shopify to Klaviyo. Klaviyo syncs historical Shopify customers and orders, so your segments work from day one.
- Import contacts by status. Subscribers as subscribed; everyone else suppressed. SMS contacts only with documented consent.
- Rebuild flows natively, improving them rather than copying them.
- Rebuild signup forms and test them for both list growth and page speed.
- Cut over flow by flow, then remove the old app and forms.
- Warm up sending, most engaged subscribers first.
- Compare results against what the old platform earned.
For a typical Shopify brand this takes a few weeks, most of which is flow rebuilding and testing.
Why the Shopify side matters
The part of a migration that email-only teams struggle with is the store. Klaviyo gets its data from Shopify and from your apps: subscription platforms, loyalty programs, reviews, and custom checkout logic. If those integrations were wired to the old platform, they need to be reconnected, and if the theme sends custom events, those need to point at Klaviyo.
When Oatly came to us, order, shipping, and subscription emails were scattered across Shopify, AfterShip, and Recharge. We moved nearly every one of them into Klaviyo, and the team could finally see the whole post-purchase journey in a single customer profile. The Oatly case study covers how.
Frequently asked questions
Can I import my Mailchimp automations into Klaviyo?
No. Contacts and lists can be imported, but automations have to be rebuilt in Klaviyo. That is usually a chance to improve them.
Will I lose subscribers when I switch to Klaviyo?
Not if you import each consent status correctly. Most losses come from importing only part of the list or from deliverability problems after a rushed first send.
How long does a Klaviyo migration take?
A few weeks for a typical Shopify store, most of it spent rebuilding and testing flows. The data import itself is fast.
Should I migrate SMS at the same time as email?
Only if your SMS consent records are complete. If they are not, launch Klaviyo SMS with fresh consent capture instead of moving an undocumented list.
Do I need an agency to migrate to Klaviyo?
Not for a small list with a few simple flows. For a Shopify Plus store with subscriptions, loyalty, or custom events, having the team that knows the store run the migration removes most of the risk.
If you are planning a move, our Klaviyo agency team runs migrations from Mailchimp, Attentive, Omnisend, and Shopify Email, and the same team maintains the Shopify store the data comes from.
