SharePoint Hub Sites: Complete Architecture Guide for Enterprise Intranets

Multi-Hub Architecture for Large Enterprises

Organisations with more than 2,000 employees often need a two-tier hub structure. A single flat list of department hubs breaks down when you have 20+ departments, regional variations, and subsidiary companies. Multi-hub architecture introduces a root hub (the company intranet home) and second-tier hubs (departments or regions) that associate to it.

As of 2023, Microsoft introduced hub-to-hub association, allowing a hub site to associate to another hub site. This creates genuine hierarchy: the EMEA HR hub associates to the corporate HR hub, which associates to the intranet home hub. Navigation and theming cascade down through the layers. Search scoping works at each level independently — users on the EMEA HR hub see EMEA-specific content; users on the corporate HR hub see all regions.

# Associate a hub site to a parent hub site
# (requires SharePoint Online Management Shell v16.0.22601+)
Add-SPOHubSiteAssociation `
  -Site "https://contoso.sharepoint.com/sites/HR-EMEA" `
  -HubSite "https://contoso.sharepoint.com/sites/HR"

# Verify the hierarchy
Get-SPOHubSite -Identity "https://contoso.sharepoint.com/sites/HR-EMEA" |
  Select ParentHubSiteId, HubSiteId

Hub Site Migration Checklist

If you're migrating from a classic SharePoint environment with subsites, converting to a hub architecture requires careful planning. The migration cannot be automated — it requires content decisions at every level of the old hierarchy.

• Audit existing subsites: list every subsite, its owner, last modified date, and visitor count from SharePoint analytics.
• Classify each subsite as: migrate as new site collection, merge into parent, archive and decommission, or migrate to Teams.
• Create new site collections for surviving subsites before migrating content. Use the SharePoint Migration Tool or Sharegate for bulk content migration.
• Register department parent sites as hubs before associating children — association order matters for navigation inheritance.
• Update all internal hyperlinks after migration. Classic SharePoint content is full of hardcoded subsite URLs that break when subsites become independent site collections.
• Test the hub search scope with representative queries from real users before go-live.
• Run a parallel period (two weeks minimum) where both old and new structures are accessible.