Synchronize domain users to Microsoft 365
1. Prepare for Directory Synchronization
Before you synchronize your users and computers from the local Active Directory Domain, review Prepare for directory synchronization to Microsoft 365. In particular:
Make sure that no duplicates exist in your directory for the following attributes: mail, proxyAddresses, and userPrincipalName. These values must be unique and any duplicates must be removed.
We recommend that you configure the userPrincipalName (UPN) attribute for each local user account to match the primary email address that corresponds to the licensed Microsoft 365 user. For example: firstname.lastname@example.org rather than email@example.com
If the Active Directory domain ends in a non-routable suffix like .local or .lan, instead of an internet routable suffix such as .com or .org, adjust the UPN suffix of the local user accounts first as described in Prepare a non-routable domain for directory synchronization.
The Run IdFix in step four (4) below, will also make sure your on-premises Active Directory is ready for directory synchronization.
2. Install and configure Microsoft Entra Connect
To synchronize your users, groups, and contacts from the local Active Directory into Microsoft Entra ID, install Microsoft Entra Connect and set up directory synchronization.
In the admin center, select Setup in the left nav.
Under Sign-in and security, select Add or sync users to your Microsoft account.
On the Add or sync users to your Microsoft account page, choose Get started.
In the first step run IdFix tool to prepare for Directory sync.
Follow the wizard steps to download Microsoft Entra Connect and use it to synchronize your domain-controlled users to Microsoft 365.
See Set up directory synchronization for Microsoft 365 to learn more.
As you configure your options for Microsoft Entra Connect, we recommend that you enable Password Synchronization, Seamless Single Sign-On, and the password writeback feature, which is also supported in Microsoft 365 for business.
There are some additional steps for password writeback beyond the check box in Microsoft Entra Connect. For more information, see How-to: configure password writeback.
If you also want to manage domain-joined Windows 10 devices, see Enable domain-joined Windows 10 devices to be managed by Microsoft 365 Business Premium to set up a Microsoft Entra hybrid join.