Branding and customisation in Microsoft 365

A consistently branded Microsoft 365 tenant signals professionalism and helps users recognise legitimate corporate surfaces. The branding surface is spread across several admin centers, with no single "brand your tenant" command. Knowing where each piece lives saves time.

Tenant-wide branding (Microsoft 365 admin center)

In `admin.microsoft.com → Settings → Org settings → Organization profile → Custom themes:

Default theme — the colour scheme and logo applied to the Microsoft 365 app launcher and top bar across Microsoft 365 web apps.
Group-based themes — different themes for different Entra ID groups (e.g., a subsidiary's branding for its users, parent company's for everyone else).

Branding here covers:

Primary logo for the top-left of Microsoft 365 web app.
Secondary logo for the app launcher.
Primary colour and text colours.
Optional "navigation bar background" image.

The Microsoft 365 sign-in page (and SAML / OIDC sign-in for apps using Entra ID) is branded in Entra admin center → Identity → User experiences → Company branding:

Background image behind the sign-in form.
Banner logo at the top of the sign-in card.
Square logo for sign-in scenarios on small surfaces.
Sign-in page text with custom messaging.
Footer links — privacy statement, terms of use.
Language overrides for multilingual orgs — different branding per locale.

Sign-in branding shows on every Microsoft authentication, including web Office, Teams, Outlook mobile, Entra-integrated SaaS apps.

SharePoint and Viva Connections branding

For the intranet experience:

Home site for the tenant — a SharePoint communication site designated as the corporate intranet root.
Site themes — colour palette and fonts applied per site, inherited from hub sites.
Site logos — per site.
Viva Connections — Microsoft Teams app branded as your intranet.

Teams branding

Limited but increasing:

Custom Teams app icon in the Teams admin center for tenant-internal pinning.
Custom Together Mode scenes (Teams Premium) for branded virtual meeting rooms.
Organisation backgrounds (Teams Premium) — branded video-call backgrounds delivered to all users.
Custom meeting templates (Teams Premium).

Outlook branding

Email signatures via cloud signatures, transport rules, or third-party signature management tools (covered in the Outlook signatures guide).

Outlook on the web has a per-user customisable theme; tenant-wide Outlook branding is limited.

Email branding via OME

Office 365 Message Encryption (OME) branded portals — for encrypted emails sent to external recipients, the OME portal can be customised with your logo, colours, sender messaging.

Operational considerations

Consistency across all of the above takes some coordination — same logo, same colours, same messaging.
Mobile preview — verify branding renders correctly on mobile, where sizing differs.
Performance — large background images can slow sign-in; optimise file sizes.
Language-specific branding — set up alternates for primary languages used.

Common mistake

The most common mistake is configuring tenant branding in the Microsoft 365 admin center but not configuring Entra ID company branding — so the sign-in page is generic Microsoft, then the post-sign-in experience is branded. Users see a transition that looks like they're moving between two different products.

Configure both. Each takes 15 minutes and pays back forever.