How To Migrate Mailchimp To Klaviyo Without Breaking Flows

A clean Mailchimp to Klaviyo migration keeps your revenue emails running while you move lists, consent, and automations into a new system. The goal is simple: bring over subscribers and unsubscribes correctly, rebuild your key Klaviyo flows with the same triggers and timing, and avoid sending duplicate messages from two places at once. Start by confirming which Mailchimp audiences and fields matter, then reconnect signup forms and your ecommerce integration so new contacts and events land in Klaviyo from day one. The most painful “broken flow” problems usually come from one overlooked detail, like a lingering Mailchimp form, integration, or automation still quietly firing in the background.

What moves over from Mailchimp to Klaviyo, and what doesn’t?

Audiences, tags, and custom fields

Your Mailchimp audiences (lists) are the easiest thing to bring over. When you connect Mailchimp to Klaviyo, you can sync contacts from those audiences into Klaviyo lists, and you can also bring over unsubscribes so you do not accidentally email people who opted out.

Where migrations get tricky is how Mailchimp stores “extra” data:

• Tags: Mailchimp tags do not reliably “auto-transfer” in a way that’s useful in Klaviyo. Plan to export tag-based groups from Mailchimp and import them into Klaviyo as profile properties (custom fields) or as separate lists, depending on how you plan to target.
• Groups / interests / merge fields: These usually need mapping. In Klaviyo, most of this becomes profile properties you can segment on and use for personalization.

If you want the cleanest setup long-term, aim to consolidate into one primary email list in Klaviyo and use properties and segments for organization, rather than creating many lists that you will have to maintain.

Campaigns, templates, and assets

In most real-world migrations, you should assume your email creative does not “move” cleanly:

• Past Mailchimp campaigns are useful as reference, but you typically rebuild templates in Klaviyo’s editor.
• Brand assets (logos, images, saved content blocks) may be reusable, but you’ll often re-upload and re-format to match Klaviyo sections and blocks.
• Any Mailchimp-specific dynamic content or merge tags will need to be replaced with Klaviyo equivalents.

This is annoying, but it’s also a good time to simplify layouts and standardize typography, buttons, and spacing.

Automations versus Klaviyo flows

Mailchimp automations do not convert into Klaviyo flows automatically. Treat this as a rebuild, not a copy-and-paste.

The good news: Klaviyo flows are usually more flexible once you recreate them. The key is to document each Mailchimp automation first, then rebuild the same behavior in Klaviyo:

• trigger (what starts it)
• timing (delays and send windows)
• filters (who qualifies)
• branching logic (if/then paths)

Until you cut over, keep a close eye on “double sending.” If a Mailchimp automation is still on while a Klaviyo flow is live, subscribers can get both.

Migration prep that prevents broken flows and double sending

Export the right lists and segments

Start by deciding what your “source of truth” will be in Klaviyo. For most teams, that means one primary email list, plus segments for targeting.

From Mailchimp, export:

• Each Audience you actively email.
• Key segments you rely on for revenue (VIP, recent buyers, high AOV, wholesale, etc.).
• Any tag-based groups that control messaging (for example: “Newsletter Only,” “Do Not Promote,” “Wholesale Lead”).

If a segment is complicated, export a snapshot anyway. It gives you a safety net while you rebuild the logic in Klaviyo. Also export email + phone (if you use SMS later), and include any fields you personalize with (first name, location, preferences).

Clean consent and suppression data

Most “broken flow” stories are actually consent problems. Before anything imports, get your suppression data clean and complete.

Make sure you have:

• Unsubscribes (global, and audience-level if applicable).
• Cleaned / bounced / invalid contacts (do not re-import as emailable).
• Any internal “do not contact” indicators (like customer service escalations).

If you operate in regulated regions, double-check what you have for marketing permission. In Klaviyo, treat consent as something you can segment on and audit, not just a checkbox you hope is right.

Inventory your current automations

List every Mailchimp automation that can send an email without you clicking “Send.” Include hidden ones like abandoned cart, post-purchase, winback, and lead capture series.

For each automation, write down:

• entry trigger and audience/segment rules
• the exact email sequence and delays
• any goal logic (when people should stop receiving it)
• any dependencies (coupon codes, product recommendations, ecommerce events)

This inventory becomes your cutover checklist. It also makes it much easier to turn off Mailchimp sends at the right moment, so Klaviyo flows can take over without duplicates.

Connecting Mailchimp to Klaviyo and understanding the sync

Setting up the Mailchimp integration

If you still need Mailchimp as a temporary bridge while you rebuild in Klaviyo, start with Klaviyo’s built-in Mailchimp integration. During setup, you choose which Mailchimp audiences to sync, and whether Klaviyo should create matching Klaviyo lists from those audiences. This choice matters because it controls what contact data and engagement history Klaviyo can associate correctly later.

Two practical tips before you click connect:

• Sync only the audiences you actually plan to email going forward (or you can bring in a lot of old, unengaged profiles).
• Decide now whether you want “audience = list” in Klaviyo, or whether you’ll consolidate into fewer lists after the initial import.

If you want the official step-by-step screens, follow Klaviyo’s guide on how to migrate from Mailchimp.

Sync timing and data scope

After connecting, data usually starts showing up within minutes, but full sync takes longer depending on list size.

In general, the integration brings over:

• Mailchimp audiences (as Klaviyo lists, if you enable that option)
• subscriber status details, including unsubscribes and contacts marked as cleaned
• limited campaign engagement history (opens, clicks, receives), rather than full campaign content

Klaviyo also runs an initial historical sync and then continues periodic syncs, so you may see totals change over the first day.

Common sync limitations to expect

Plan around these limits so you do not build flows on missing data:

• Tags do not automatically sync in a usable way. Export and import tag-based groups separately if you need them for segmentation.
• Only certain standard contact fields sync cleanly. Many custom fields, preferences, and groupings need manual mapping into Klaviyo profile properties.
• Campaign history sync is limited (typically recent activity) and only for campaigns that are fully sent. It’s for targeting and segmentation, not recreating old campaigns.
• Deleting a contact in Mailchimp does not mean they disappear from Klaviyo. Treat Klaviyo as its own database once you start importing.

Importing subscribers, tags, and custom properties into Klaviyo

Mapping fields and profile properties

Before you import anything, decide what each Mailchimp field should become in Klaviyo. In Klaviyo, the cleanest pattern is: email/phone as identifiers, and everything else as profile properties you can segment on and personalize with.

A practical mapping approach:

• Keep standard fields standard (Email, First Name, Last Name, Phone).
• Convert Mailchimp merge fields, groups, and “preferences” into clear profile properties (e.g., favorite_category, customer_type, signup_source).
• For Mailchimp tags, either:
  • import them as a single property (e.g., mc_tags), or
  • create specific boolean properties you can filter easily (e.g., is_wholesale = true).

When uploading a CSV, Klaviyo lets you map each column to an existing property or create a new field during import. Import properties without changing subscription status, so you don’t accidentally re-subscribe people who opted out.

Recreating segments from Mailchimp logic

Don’t try to rebuild every segment on day one. Start with the segments that control sends and revenue.

In Klaviyo, segments usually fall into two buckets:

• Properties about someone (profile properties like tags, preferences, location).
• What someone has done (or not done) (events/metrics like placed order, started checkout, viewed product).

Recreate Mailchimp segments by translating the intent, not the exact UI steps. For example, a Mailchimp “VIP” segment might become “Placed Order at least 3 times” plus “Revenue greater than X” over a set time window. Save each segment, then give it time to populate before scheduling a campaign.

Handling unsubscribes and suppressions correctly

This is where you prevent complaints and protect deliverability.

If you’re syncing from Mailchimp using Klaviyo’s integration, unsubscribed contacts should flow into Klaviyo’s suppression list automatically. For manual imports, you can upload historical unsubscribes and bounces directly into Klaviyo’s suppression list, so they’re blocked from marketing sends even if they exist on a list.

One key rule during CSV imports: if you import a list and tell Klaviyo to update subscription status, you can unintentionally mark everyone as subscribed. For migrations, it’s usually safer to import contacts and properties first, then manage consent intentionally (and conservatively) afterward.

Moving email templates and brand assets into Klaviyo

Rebuilding templates in the Klaviyo editor

Plan to rebuild, not “port,” your Mailchimp templates. The HTML structures are different, and a direct copy often creates spacing bugs, mobile issues, or inconsistent fonts.

Start with 2 to 4 core Klaviyo templates you can reuse:

• Newsletter / campaign template
• Promo template (sale, launch, seasonal)
• Transactional-style layout for flows (welcome, post-purchase, winback)

Pull your brand basics from what already performs well: logo, color codes, button style, header spacing, and product image rules. Then recreate those as reusable sections or saved blocks. If you want fewer surprises during cutover, keep the first Klaviyo versions visually close to Mailchimp, then iterate after everything is stable.

Replacing Mailchimp merge tags and dynamic content

Mailchimp merge tags and Klaviyo variables are not interchangeable, so any personalization needs a careful swap. Go through each template and identify:

• First name (and a fallback when it’s blank)
• Preference fields (category, gender, region, etc.)
• Conditional content blocks (show one offer for VIPs, another for new subscribers)

In Klaviyo, these usually pull from profile properties or event data. If a piece of personalization depends on an ecommerce event (like order items), make sure your store integration is already sending that data into Klaviyo before you rely on it in a flow email.

Updating footer, unsubscribe, and preference links

Do not copy your Mailchimp footer as-is. Rebuild it using Klaviyo’s required links so compliance and deliverability stay intact.

Before sending anything live, confirm:

• The unsubscribe link is Klaviyo’s unsubscribe, not a leftover Mailchimp link.
• Any “manage preferences” link points to your Klaviyo preference page (if you use one).
• Your physical address and brand identity details are correct.

This is also a good time to standardize your footer across templates, so every campaign and flow email has consistent compliance elements.

Recreating automations as Klaviyo flows without losing behavior

Translating triggers, filters, and timing

When you rebuild Mailchimp automations in Klaviyo, match the behavior in three layers: trigger, qualification filters, and timing.

Start with the trigger. In Klaviyo, most revenue flows should be triggered by an event (like Started Checkout or Placed Order) rather than “joins list,” unless it’s a welcome series. Next, add filters that protect the flow from bad sends, such as “is not suppressed,” “has not placed order since starting flow,” or “is not already in another flow.”

Then replicate timing with intent. A “Wait 1 day” in Mailchimp may need a Klaviyo time delay plus send time window (for example, only send between 9am and 6pm in the recipient’s time zone). If you used “send immediately” before, consider a short delay (5 to 30 minutes) for event-based flows to let purchase data finish syncing.

Preserving branching and conditional logic

Mailchimp’s branching often maps to Klaviyo’s Conditional Split (based on profile or event data) and Trigger Split (based on how someone entered).

To preserve logic, document each decision point in plain language first. Example: “If customer is VIP, show offer A. If not, show offer B.” Then implement it with a split and keep each branch as similar as possible in length and timing. Also add explicit exit conditions, so customers do not receive emails that no longer apply after they convert.

Flow-specific gotchas that break sends

Most flow failures are not “email problems.” They’re missing data or wrong filters.

Common causes:

• The flow trigger fires, but the message is held because Smart Sending or frequency settings block it.
• The flow expects ecommerce events, but the integration is not sending the event you chose.
• A filter excludes almost everyone (for example, checking a property that exists in Mailchimp but was not imported into Klaviyo).

Before turning any flow live, run it in draft and test with internal profiles that have realistic properties and events.

UTM, coupon, and product feed dependencies

If your Mailchimp automation relied on auto-added UTMs, dynamic coupons, or product recommendations, rebuild those dependencies deliberately.

Check three things:

• Your UTM structure is consistent across flows and campaigns (and doesn’t duplicate parameters).
• Coupon logic matches the original rules (single-use vs multi-use, expiration, minimum spend).
• Product blocks pull from the right catalog source and have fallbacks, so emails do not render empty when an item is unavailable.

QA and cutover steps to ensure flows run safely

End-to-end testing with internal profiles

Before you switch anything on, test like a customer would. Create 2 to 3 internal Klaviyo profiles with different traits (new subscriber, repeat buyer, VIP). Use real inboxes you can check across Gmail and Outlook if possible.

Then run each flow end-to-end:

• Trigger the event (signup, checkout start, purchase) using a test order or a low-cost product.
• Confirm the person qualifies (they are not suppressed, they meet filters).
• Verify timing: delays, send windows, and time zone behavior.
• Open the email on mobile and desktop. Check images, buttons, dynamic blocks, and personalization fallbacks.

Also check reporting basics. If a message sends but the event and attribution look off, fix that now rather than after you scale volume.

Deliverability warmup basics after switching platforms

A platform switch can change sending infrastructure and reputation signals, even if your domain stays the same. Start conservatively.

For the first 1 to 2 weeks, prioritize:

• sending to your most engaged subscribers first
• keeping flow volume steady (welcome, abandoned cart, post-purchase), then layering on campaigns
• watching hard bounces, spam complaints, and unsubscribe rate closely

If you have a large list, avoid blasting the full file on day one. A gradual ramp is usually safer than a sudden spike.

Sunsetting Mailchimp to avoid duplicate emails

Cutover is less about “turning Klaviyo on” and more about “turning Mailchimp off” in the right order.

Do this in sequence:

1. Pause Mailchimp automations that overlap with Klaviyo flows.
2. Disable or replace Mailchimp signup forms, popups, and embedded forms so new leads enter Klaviyo.
3. Confirm your ecommerce integration is feeding events into Klaviyo reliably.
4. Turn on Klaviyo flows one by one, starting with the highest priority.

Finally, keep Mailchimp access for reference during the first week, but remove any remaining sends so subscribers never receive two versions of the same automation.