Syncing custom objects between Salesforce and HubSpot is one of the trickier parts of running both systems. HubSpot's Salesforce integration can sync custom objects, but it takes deliberate field mapping and association rules — get those right and your records stay aligned in both systems, get them wrong and you create duplicates and broken links that take weeks to untangle. Standard objects like contacts and accounts are the easy part. Custom objects are where teams trip up. Here's the practitioner's read on doing it cleanly.
Can you actually sync Salesforce custom objects to HubSpot?
Yes — HubSpot's Salesforce integration supports custom object sync, but it has to be configured object by object, not switched on all at once. A custom object is any record type your team built beyond the standard ones — think "Subscriptions," "Properties," or "Projects." For the sync to work, the object needs to exist in both systems with matching fields, and you have to define how records map and associate across the two. HubSpot reads the Salesforce object, you choose which fields move and in which direction, and the integration keeps them in step. The work isn't clicking "sync" — it's deciding the rules before you do.
How does field mapping work between the two systems?
You map each Salesforce field to a matching HubSpot property, and the field types have to line up or the sync fails. A text field maps to a text property, a date to a date, a dropdown to a matching set of options. Mismatches are the most common cause of sync errors — a picklist value in Salesforce that doesn't exist in HubSpot's property, or a number field mapped to text. You also set direction per field: two-way for fields both teams edit, one-way for fields that should only ever flow from the system of record. Worked example: a Subscriptions object syncs plan name and renewal date two-way, but "Salesforce ID" stays one-way into HubSpot as a read-only reference — so nobody in HubSpot can accidentally overwrite the source key.
How do you keep associations intact?
Map the relationship fields, not just the data fields, so a synced custom object connects to the right contact or company on both sides. A custom object is only useful if it's linked — a Subscription tied to the right Company, a Project tied to the right Contact. In Salesforce those links are lookup or master-detail fields; in HubSpot they're associations. If you sync the object's data but not its relationships, you land thousands of orphaned records floating with no parent. So confirm the parent records (companies, contacts) are already synced and matched on a unique key first, then sync the custom object so it can attach to records that exist. Order matters: parents before children, always.
What should you check before turning the sync on?
Test on a small set, confirm matching keys, and decide your system of record before the full sync runs. Pick a handful of records, sync them, and inspect both systems: did the fields land correctly, did associations form, are there duplicates? Confirm every record has a stable unique identifier the integration can match on, so it updates instead of duplicating. And agree which system owns each field — when both sides can edit and you haven't set direction, the last write wins and data quietly flips. This is the order we follow with clients: model the objects in both systems, map fields and relationships, test small, then scale. Skip the test batch and you debug at full volume.
The IV-Lead take
Custom object sync fails for boring reasons, not exotic ones: mismatched field types, parents synced after children, and no agreement on which system is the source of truth. Teams reach for the integration expecting magic and get a mirror of their own unclear data model. The integration is honest — it syncs exactly the structure you give it, including the gaps. So the real work happens before you connect anything: clean objects in both systems, explicit mapping, and one decision per field about who owns it. Do that and the sync is quiet and reliable. Skip it and you'll spend more time fixing the sync than you saved by having one.
Running Salesforce and HubSpot side by side? Book a 30-minute portal audit — we'll tell you straight whether your objects are ready to sync and what to fix first. For the bigger picture, see how we approach HubSpot integrations and data sync.
Frequently asked questions
Does HubSpot's Salesforce integration support custom objects on every plan?
Custom object sync requires specific HubSpot subscription tiers and the Salesforce integration enabled on both sides. Check your plan level before scoping the project, since the available sync features differ by tier.
Can I sync a custom object two ways?
Yes, you can set fields to sync in both directions. But for keys and source-of-record fields, keep them one-way so neither team can overwrite the other's data by accident.
Why are my synced records showing as duplicates?
Almost always because the integration has no reliable unique key to match on, so it creates a new record instead of updating the existing one. Confirm a stable matching identifier exists in both systems before syncing.
What happens to associations if the parent record isn't synced yet?
The custom object lands without its link and becomes an orphan. Always sync and match the parent records — companies and contacts — before syncing the custom objects that attach to them.
