In Brief: Connecting Mailchimp to HubSpot and migrating from Mailchimp to HubSpot are two different projects. HubSpot offers two Mailchimp apps: Campaign Sync shows Mailchimp email activity on HubSpot contact records, while Data Sync keeps contacts and mapped fields aligned, but leaves tags, groups and engagement behind. A real Mailchimp to HubSpot migration means deciding what moves, what breaks and what gets rebuilt, starting with unsubscribes, before the first email leaves HubSpot.
Few teams leave Mailchimp because the emails stop working. They leave because email lives in one tool and the pipeline lives in another. Sales can't see who opened last week's campaign, marketing can't see which subscribers turned into customers, and every list export becomes a small reconciliation project.
On paper, the move looks simple: export the audience, import the contacts, rebuild a few templates. In practice, a Mailchimp to HubSpot migration touches three things a CSV file doesn't carry cleanly: consent, segmentation and engagement history.
This guide breaks down what each of HubSpot's two Mailchimp apps actually does, what moves across, what breaks along the way, and how to plan the switch so your first HubSpot send reaches the right people.
Why Teams Move from Mailchimp to HubSpot
The reason is rarely the email editor. It is the gap between email and everything else. In HubSpot, a subscriber is a contact record: the same record a sales rep works, a workflow reads and a report counts. Email engagement sits next to deals and lifecycle stage, so a HubSpot implementation can trigger follow-up from a click, score a lead on campaign activity, and show which newsletters actually contribute to pipeline.
That shift is also where most migration problems start. Mailchimp organises people into audiences, each with its own fields, tags and unsubscribe status. HubSpot organises everything around one contact database, with properties, lists and subscription types layered on top. The same structural mismatch shows up in other moves into HubSpot, as we covered in our Attio to HubSpot migration guide: the records transfer easily, but the logic around them doesn't.
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Integration, Data Sync, or Full Migration: Which One Do You Need?
HubSpot publishes two Mailchimp apps, and they do different jobs. It is the same pattern we described in our HubSpot Jira integration post: two apps with similar names, and the right choice depends on what you need to keep in sync.
| Compare | Campaign Sync | Data Sync | Full migration |
|---|---|---|---|
| Best for | Sending from Mailchimp while seeing activity in HubSpot | Keeping contacts aligned while both tools are live | Moving email marketing into HubSpot for good |
| Contact direction | HubSpot to Mailchimp | One-way or two-way | One-time move into HubSpot |
| Email activity in HubSpot | Sends, opens, clicks and bounces on existing contacts | Not included | Only what Campaign Sync captured before switch-off |
| Tags and groups | Not synced | Not synced | Rebuilt as properties and lists |
| Worth checking first | Required merge tags in the Mailchimp audience | Data Hub Starter or above | Marketing contact allocation in HubSpot |
| Long-term role | Transition tool | Transition or coexistence tool | End state |
App capabilities as listed on the HubSpot App Marketplace and in HubSpot's documentation, October 2026.
Neither app is a migration on its own. Data Sync moves the people, Campaign Sync moves the behaviour, and neither touches consent logic, segments or automations. During a phased switch, many teams run Campaign Sync for engagement visibility, use a planned import or Data Sync for the contacts, and retire Mailchimp once HubSpot is doing the sending.
What Moves from Mailchimp to HubSpot
The migration map at the top of this guide shows where each part of a Mailchimp account ends up. Two details decide whether those moves land cleanly.
Matching. Both tools identify a contact by email address, so the email is the key for every import and sync. Someone who sits in three Mailchimp audiences becomes one HubSpot contact, and whichever record arrives last can overwrite the others, which is why deduplication belongs in the plan, not in the clean-up.
Tags and groups. Groups usually work best as a multiple checkbox property, because they describe a fixed set of interests. Tags are messier: the ones you report on become properties, the ones you only used to pick a send audience become static lists, and the ones nobody remembers creating can stay behind.
Mapping Fields in Mailchimp Data Sync
If you use Mailchimp Data Sync during the transition, the field mapping screen is where the contact structure is decided:
Mailchimp Data Sync field mapping between Mailchimp and HubSpot contacts
What the screen doesn't tell you is when the sync starts. According to HubSpot's data sync documentation, the initial sync begins as soon as the settings are saved, not only when you switch the sync on. Filters only limit which records sync the first time; once a contact has synced, it keeps syncing. Settle the matching and conflict rules on a test audience before anyone saves the configuration on live data.
What Breaks in a Mailchimp to HubSpot Migration
Most problems in this migration don't show up as errors. The sync reports success, the import completes, and the gaps only appear when someone looks for data that should be there.
01
Required merge tags stop the sync
When Campaign Sync sends contacts to Mailchimp, it only passes first name, last name and email. HubSpot's Mailchimp documentation confirms it can't sync to an audience with required merge tags, because it has no value to send for them.
02
Tags and groups don't travel
Data Sync moves contacts and mapped fields, but Mailchimp tags and groups are explicitly excluded. Years of segmentation logic stays behind unless it is rebuilt as HubSpot properties and lists.
03
Engagement history is short
Campaign Sync only brings in activity from campaigns sent within 30 days before the connection, skips A/B tests and Customer Journeys, and only attaches events to contacts that already exist in HubSpot.
04
Unsubscribes don't map one to one
Mailchimp tracks unsubscribe status per audience. HubSpot manages consent through subscription types on one database. A contact who unsubscribed from one audience can look perfectly reachable after the move.
05
The plan requirement appears late
Data Sync requires Data Hub Starter or above. It's easy to discover this only at installation, after the migration plan has already assumed a two-way sync.
How to Plan a Mailchimp to HubSpot Migration
A clean migration is mostly decided before any data moves. The sequence below is the one we follow, and the order matters more than the tooling.
BEFORE ANYTHING MOVES
Audit the Mailchimp account. List every audience, merge field, tag, group, segment, Customer Journey, signup form and connected integration. Mark what is still in use and what can be retired, so the HubSpot setup isn't built around clutter. Then export each audience: Mailchimp splits the export into separate files for subscribed, unsubscribed, non-subscribed and cleaned contacts, and each file needs its own decision in HubSpot.
Clean the data and set consent rules. Deduplicate contacts that appear in more than one audience, decide which HubSpot subscription types replace each audience, and map every unsubscribe to the right opt-out. This is the phase where data cleaning pays for itself.
Design the HubSpot data model. Create properties for merge fields, tags and groups before the import, and decide which segments become active lists. Unmapped fields are one of the most common gaps after any move into HubSpot, as our Pipedrive to HubSpot migration case showed.
THE MOVE
Test with a sample. Import or sync one small audience first. Check properties, list membership and opt-out status on real records before anything else moves. A failed test costs minutes; a second full import on top of a partial one costs days, which is exactly the situation we untangled in an Insightly to HubSpot migration.
Migrate and run in parallel. Move the full contact base, keep Campaign Sync running while Mailchimp is still sending, and use Data Sync only if both tools need to stay live for a period.
CUTOVER
Authenticate the sending domain. Connect your email sending domain in HubSpot before the first send. Until it is connected, HubSpot sends from a HubSpot-managed domain instead of your own, and inbox providers such as Gmail and Yahoo expect DKIM, SPF and DMARC on bulk email. Skipping this step is one of the quickest ways to lose the deliverability you had in Mailchimp.
Switch and close. Send the last Mailchimp campaign, export the campaign reports you want to keep, then disconnect the apps and close the Mailchimp account.
After Go-Live: Forms, Templates and Automations
Moving the contacts is only half the switch. The pieces that keep email marketing running day to day have to be rebuilt in HubSpot, and each one is a chance to drop what no longer works.
Forms. Replace Mailchimp signup forms with HubSpot forms so new subscribers land in the CRM with consent captured from the first submission. If a third-party form has to keep feeding Mailchimp during the transition, HubSpot supports connecting non-HubSpot forms to a Mailchimp list until the cutover.
Templates. HubSpot Smart Transfer can recreate HTML email templates from Mailchimp. Review each one before use: footers, unsubscribe links and brand settings rarely survive a transfer exactly as intended.
Automations. Customer Journeys don't transfer, so rebuild them as HubSpot workflows around the goal of each journey, not step by step. Many journeys turn out to be redundant once the data model is clear.
Contact tiers. Not every Mailchimp record needs to become a billable HubSpot contact. Each file in the Mailchimp export maps to a different treatment:
| Mailchimp status | In HubSpot |
|---|---|
| Subscribed | Marketing contact, opted in to the matching subscription types |
| Unsubscribed | Opt-out import, or opt-outs on the matching subscription types if they still receive other email |
| Non‑subscribed | Non-marketing contact, or left out |
| Cleaned | Never a marketing contact: left out, or added to the opt-out import |
An opt-out import blocks those addresses from future marketing emails without creating them as contacts, so they don't add to your billable total. The same principle runs through our Zoho to HubSpot migration guide: decide what each record is for before it lands, not after.
"The riskiest contact in a Mailchimp to HubSpot migration is the one who already unsubscribed. If those opt-outs don't land in the right HubSpot subscription types before the first send, you're emailing people who have already said no," says Stefan Loncar, CEO of Loncom Consulting.
When to bring in a partner. A single clean audience is a manageable in-house project. Several overlapping audiences, a CRM migration running at the same time, or strict consent requirements under UK GDPR are usually the point where a HubSpot partner saves more time than it costs.
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FAQ
How do I migrate from Mailchimp to HubSpot?
Audit the Mailchimp account, clean and deduplicate contacts across audiences, map unsubscribes to HubSpot opt-outs and subscription types, create HubSpot properties for merge fields, tags and groups, test with one audience, then move the full contact base and rebuild forms, templates and automations. The data transfer itself is the shortest part of a Mailchimp to HubSpot migration.
Does the HubSpot Mailchimp integration sync both ways?
It depends on the app. Mailchimp Campaign Sync sends contacts from HubSpot to Mailchimp and brings email activity such as sends, opens, clicks and bounces back into HubSpot. Mailchimp Data Sync can sync contacts in both directions, but it does not sync tags, groups or email opens and clicks.
What is the difference between Mailchimp Campaign Sync and Mailchimp Data Sync?
Campaign Sync is built for teams that keep sending from Mailchimp and want engagement visible in HubSpot. Data Sync keeps contact records and mapped fields aligned between both tools, one-way or two-way, and requires Data Hub Starter or above. Neither one migrates segments, consent logic or automations.
Can I import Mailchimp contacts into HubSpot without emailing people who unsubscribed?
Yes, but only if unsubscribes are handled deliberately. Export unsubscribed contacts from each Mailchimp audience and bring them in as an opt-out import, which blocks future marketing emails to those addresses, or opt them out of the matching HubSpot subscription types if they should still receive other email. Leaving them out of the migration entirely is riskier, because they can return later through a form or a list upload with no opt-out on record.
Will I lose my Mailchimp campaign history?
Most of it stays in Mailchimp. Campaign Sync only brings activity from campaigns sent within 30 days before the connection, excluding A/B tests and Customer Journeys. Export the campaign reports you need before closing the Mailchimp account.
How long does a Mailchimp to HubSpot migration take?
A straightforward migration with one or two clean audiences typically takes two to four weeks. Several overlapping audiences, years of tags and groups, heavy automation or a CRM move running alongside it usually stretch that to six to eight weeks. With Data Sync, HubSpot notes that initial syncs of very large databases can take several days.
How does Loncom handle Mailchimp to HubSpot migrations?
As a HubSpot Diamond Solutions Partner, Loncom Consulting starts with the data model and consent rules, not the import. We audit the Mailchimp account, map audiences, tags and unsubscribes to HubSpot properties, lists, opt-outs and subscription types, test on a sample, and rebuild forms and automations so the first HubSpot send goes only to people who should receive it.
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