How to migrate SharePoint to Microsoft 365 from on-premises

Hosting data on your own servers gives organizations full control over infrastructure, security configuration, and customization. But it also requires maintaining servers, storage, patching, and upgrades as the environment grows. But that control comes at a cost: On-premises also means maintaining servers, storage, patching, and upgrades as your environment grows.

While Microsoft isn’t phasing out SharePoint on-prem, extended support for SharePoint Server 2016 and 2019 ends on July 14, 2026. After that, organizations running unsupported versions won’t receive security updates, patches, or technical support for those versions. 

For some teams, that deadline is a turning point. They can upgrade to a supported version like SharePoint Server Subscription Edition (SE) or migrate SharePoint to Microsoft 365 (SharePoint Online) to reduce infrastructure overhead and modernize their environment.

If you’re planning an on-prem SharePoint migration, understanding the steps, risks, and planning considerations upfront will help you avoid delays and unexpected issues. And while tenant-to-tenant migrations follow a different process, many of the same principles still apply.

Why migrate SharePoint files to M365?

There are many drivers for moving from SharePoint on-premises to Microsoft 365. Here are some of the biggest:

• Scalability: Storing files on-premises means purchasing and maintaining expensive new servers as your business grows. But when it’s hosted in the cloud, you can easily scale your SharePoint site as demand increases. 
• Security: M365 features several security enhancements over on-prem storage. These include Conditional Access, Microsoft Defender, Entra ID identity protection,and Microsoft Purview compliance and data protection tools.
• Lifecycle management: Microsoft automatically updates SharePoint Online, saving you the time, money, and effort it would take to maintain your own servers. Microsoft 365 also integrates with Microsoft Purview retention and records management policies, allowing organizations to manage data lifecycle and compliance at scale.
• M365 integrations: As part of M365, SharePoint Online integrates with Office Online, allowing users to create and edit files from their browser. Microsoft Entra ID single sign-on (SSO) capabilities give secure access to files and folders across multiple applications with one set of credentials.
• End of support: One major driver for moving away from older SharePoint versions is the July 14, 2026, deadline for SharePoint Server 2016 and 2019. After that date, those versions won’t receive security updates or official assistance. SharePoint Server Subscription Edition will remain supported, but running outdated software can increase security, compliance, and operational risks.

Common migration scenarios

If you’re moving from SharePoint on-prem to M365, your migration strategy will depend on how your current environment is set up. Here’s an overview of the most common scenarios.

Fully on-prem to SharePoint Online 

In this scenario, all sites, libraries, and content live on local servers. Moving to M365 means rebuilding your information architecture in SharePoint Online and migrating content into a cloud-based tenant. This shift affects authentication, infrastructure planning, and how you handle identity management.

Hybrid to fully online

Some organizations run a hybrid model, with content split between on-premises servers and SharePoint Online. Migrating fully to M365 requires consolidating content into a single tenant, resolving duplicate structures, and aligning permissions across environments.

Regardless of your starting point, migrating SharePoint to Microsoft 365 isn’t just a file transfer. It impacts:

• Authentication and identity (for example, shifting from on-premises Active Directory to a hybrid identity model, where identities are synchronized to Microsoft Entra ID using tools like Microsoft Entra Connect.)
• Tool selection and limitations, since not all migration tools support legacy workflows or customizations
• Cutover planning, including downtime, user communication, and phased vs. big-bang approaches
• Metadata, workflows, and custom solutions, which may not translate directly to SharePoint Online

Governance and site architecture, especially if you’re modernizing alongside the move

Common migration challenges

Like every IT project, migrating from SharePoint On-Premises to M365 involves an element of risk. Here are the potential pitfalls you need to be aware of.

Broken permissions

Complex permission structures can be tricky to copy over to a new environment. Failing to map things correctly can lead to inconsistencies or lost access rights, meaning users won’t be able to access critical content. Any differences in user account identifiers between on-prem and cloud environments can complicate things even further.

Metadata loss

Moving to SharePoint Online isn’t just a file transfer. SharePoint Online supports the same core metadata model as SharePoint Server, but certain legacy features, field types, and customizations used in on-prem environments may not be supported in the cloud.

Common challenges include:

• Deprecated field types or legacy templates
• Classic features not supported in modern SharePoint
• Large list performance considerations such as  the 5,000-item view threshold
• Custom workflows or solutions without direct cloud equivalents

Because SharePoint Online has different architectural limits and modern experiences, not every field type or customization translates directly from on-prem environments. A migration tool for SharePoint like ShareGate Migrate helps preserve supported metadata, structure, and permissions while flagging elements that require remediation. Reviewing your information architecture before you migrate SharePoint to M365 ensures your target environment is optimized for the cloud—not just a copy of your legacy setup. 

Downtime and user disruption

A SharePoint migration doesn’t always require full system downtime. In many cases, content can be migrated in the background while users continue working in the source environment. The key disruption point is cutover—when users switch from on-prem SharePoint to SharePoint Online.

Your cutover strategy will determine how much impact users experience. A “big bang” approach moves everything at once and transitions all users on the same day. This can simplify coordination but requires careful planning and clear communication.

A phased migration moves content in waves, such as by department, site collection, or business unit. This reduces risk and allows for validation between stages, but it extends the overall timeline and may require temporary coexistence planning.

Losing sensitivity labels or compliance data during transfer

Microsoft defines sensitivity labels as a way to classify and optionally protect content, such as files, emails, sites, and Teams. Organizations typically configure labels like Public, General, Confidential, or Highly Confidential and tie them to policies that enforce encryption, access restrictions, or content markings. 

Similarly, if you lose important compliance signals such as audit logs, retention labels, or classification metadata, you may undermine your ability to demonstrate compliance and, in some cases, increase your regulatory risk under laws like HIPAA or GDPR.

To reduce that risk, use a migration tool that supports Microsoft Purview sensitivity labels. ShareGate Migrate maps Microsoft Purview sensitivity labels during migration so content keeps the correct classification, encryption, and permissions in the destination tenant.

How to migrate SharePoint: Pre-migration planning and assessment

A successful migration starts with a detailed assessment of your existing environment. Before you move anything, you need a clear picture of your infrastructure, customizations, and dependencies.

• Assess your farm and architecture: Inventory your SharePoint farm, including web applications, site collections, content databases, and service applications. Document storage quotas, database sizes, and any large lists that may be affected by SharePoint Online limits.
• Review customizations and legacy components: Identify custom solutions, sandboxed code, third-party add-ins, InfoPath forms, and classic workflows. Not all customizations have direct equivalents in SharePoint Online, so you may need to redesign or retire them. 
• Audit users, permissions, and authentication: Verify your authentication model and identity configuration. On-prem migrations typically require farm-level or administrative access to the source environment, along with appropriate permissions in the destination Microsoft 365 tenant. Review orphaned users, broken permissions, and legacy groups before migration.
• Check file and structural constraints: Evaluate file path lengths, unsupported characters, large libraries, and metadata structures that may conflict with SharePoint Online limits.
• Use a migration tool: Manual exports increase risk and complexity. A migration tool like ShareGate Migrate provides pre-migration assessment and reporting that helps IT teams understand sites, libraries, permissions, and content before anything moves. This visibility helps surface potential migration issues early, so teams can plan scope and reduce surprises during execution.

Choosing the right SharePoint migration tool

Manually copying over files just isn’t feasible for most migrations. Thankfully, there are tools available to help streamline the process. For migrating on-prem SharePoint Server to Microsoft 365, your main Microsoft option is the free SharePoint Migration Tool (SPMT). Many organizations also use third-party tools like ShareGate Migrate for additional flexibility.

Microsoft SharePoint Migration Tool (SPMT)

SPMT is a free SharePoint migration tool from Microsoft that you can use to automate SharePoint migrations, including on-prem to M365 moves. It’s good for straightforward, lift-and-shift migrations. For complex, heavily restructured, or very large projects, many organizations prefer more feature-rich third-party tools. 

The basic process for using SPMT is:

• Install and configure: Download and install the tool from Microsoft. Adjust the various configuration options according to your migration needs. This includes user mapping and file version retention. SPMT supports migrating SharePoint content, lists, libraries, metadata, permissions, and versions. Legacy workflows such as SharePoint Designer or SharePoint 2010 workflows typically need to be rebuilt manually in Power Automate after migration.
• Run a pre-migration assessment: Use the SharePoint Migration Assessment Tool (SMAT) to scan your on-prem farm and SPMT’s “Scan and assess a SharePoint site” step for specific sites. These scans generate reports showing potential migration issues and limitations you should address before migrating.
• Run the migration and verify reports: Finally, create a migration task with the SharePoint Migration Tool to test whether data migrated properly. Check the reports generated at the end of the process to confirm everything has been completed successfully.

Third-party migration tools

Third-party tools, such as ShareGate Migrate, make the migration process much easier. 

For larger or more complex on-prem to M365 migrations, teams often layer PowerShell automation and additional scripts around SPMT to manage many jobs and handle edge cases. ShareGate Migrate gives you a simple, reliable way to move your data to Microsoft 365—whether you’re migrating from on-premises or going tenant-to-tenant. It’s built to handle the complexity of real Microsoft 365 environments while keeping the process fast, predictable, and easy to control.

Beyond transferring data, ShareGate Migrate helps you modernize your environment as you go. You can migrate everything with full fidelity—preserving structure, metadata, permissions, and versions, while allowing Microsoft Purview sensitivity labels to be mapped—and use built-in reporting and bulk edits to validate results, resolve issues, and  optimize what you bring into your new workspace. This gives you a clearer, more organized Microsoft 365 environment from day one, without extra tools or added friction.

Migrate SharePoint to M365 the right way

Your SharePoint to M365 migration project doesn’t have to be complex. With the right planning and the help of powerful tools like ShareGate Migrate, your team can ensure a smooth transfer that preserves critical data and permissions and minimizes downtime. 

Book a personalized demo with one of our experts to start your migration journey with confidence.