Connect Marketo Custom Objects with Salesforce Custom Object

[lakshyayadav1]

We have a Custom Object in SFDC that we need in Marketo as well but the default sync would be a read-only sync. It will only enable us to read the custom object in Marketo. However, we need to make changes in the Salesforce Custom Object from Marketo as well. 

Is there any way we can connect Marketo Custom Objects with the Salesforce Custom Objects in a bi-directional sync?

[Sant_Singh_Rath · Accepted solution]

Marketo can sync Salesforce Custom Objects, but that sync is read-only from the Marketo side. You can use the data in filters and triggers and for segmentation or automation, but Marketo cannot create or update Salesforce Custom Object records. This is a platform limitation, not a setup issue. Unlike Leads and Contacts, Salesforce Custom Objects simply do not support write-back from Marketo.

Option 1: If the update logic can be mapped to Salesforce Lead or Contact fields, Marketo can update those fields. From there, Salesforce Flow, Process Builder, or Apex can take over and update the related Custom Object.

Option 2: Build a custom integration where Marketo updates a Marketo Custom Object or sends data via API, and a middleware layer or Salesforce Apex handles writing those changes back to the Salesforce Custom Object.

If bi-directional updates are a hard requirement, an API-driven or Salesforce-side solution is the only path. There is no native Marketo capability today that supports two-way sync for Salesforce Custom Objects.