Guide to your organization’s branding in Microsoft O365

Refer To play with branding in Microsoft 365, you need one of the following licenses:

Microsoft Entra ID P1 or P2
Microsoft 365 Business Standard (or higher)
SharePoint (Plan 1)

and an account with the Global Administrator privileges. If you meet these prerequisites, there are two places to visit to start the customization:

This is where you can fully customize Microsoft 365 login page with company branding.

To access those settings, sign in to the Microsoft Entra admin center, use the left-hand menu to navigate to Identity > User experiences > Company branding, and click Edit to open customization settings. If you don’t see some of the menu items, click Show more to expand the navigation.

If you’re used to doing things with Azure Portal, you can access Azure company branding settings there, as well. Click Microsoft Entra ID on the welcome screen and choose Company branding from the left-hand navigation menu.

Here, you can configure the basic graphical elements of your sign-in page:

Favicon – you can replace the default 4-square Microsoft logo favicon (the icon that appears on the browser’s tab) with a custom one. You need to use a PNG, JPG or JPEG file with a size of up to 5KB and dimensions of 32x32px.
Background image – use this setting to upload the big login screen image in PNG, JPG or JPEG format. The maximum file size is 300KB and the max resolution – 1920x1080px. A good idea is to use a photo of your organization’s building or a local tourist attraction.
Page background color – define the color that’ll be shown on slow connections to your sign-in page before the background image loads. You can ask a graphic designer or marketing specialist about a HEX or RGB values for one of your company colors, or use a color picker on your logo in almost any image editing software.

Here you can configure the following layout-related settings:

Template – choose the one of the two built-in sign-in page layouts. If you want to put your background image in the limelight, select Partial-screen background.
Header & Footer – lets you enable header & footer on the sign-in page. Header can show your logo, while footer provides a space for links to your organization’s legal documents (see next section for more details). To configure settings on the two next tabs (Header, Footer), you need to enable those elements first.
Custom CSS – it lets you finely customize all aspects of the sign-in page (see image at the end of this section) by uploading a Cascading Style Sheet (CSS) file. To prepare the file, consult this Microsoft reference article (or send the link to Marketing) which lists CSS classes for each and every element of the sign-in page.

If you’ve enabled header & footer for your Microsoft 365 sign-in page, the following settings will be available to you on the two next tabs:

Header logo – upload the logo image to be shown in the header section of the sign-in page. Prepare a 245x36px image with a maximum size of 10KB and in one of the following formats: PNG, JPG, JPEG.
Privacy & Cookies and Terms of Use – you can choose if you want to display links to these legal documents of your organization on the sign-in page’s footer. If you select a checkbox, you’ll need to add the link to a given document as well as the linked text.

The sign-in form is the white area where a user types in their credentials and the Sign in / Next / Back buttons are shown.

Banner logo – here you can add your company’s logo that’s going to appear on top of the sign-in box. You’ll need a 245x36px PNG, JPG or JPEG image with a maximum file size of 50KB.
Square logo (light & dark theme) – lets you add a square company logo. It appears in Windows and Entra ID (Azure AD) sign in form, for example when your users sign in to Microsoft 365 from a third party desktop app. If your logo fits the dark theme well, use just the first setting. The image file limits are as follows: 240x240px and 50KB.
Username hint text – a web browser can display a hint text in the username input field. You can specify it here.
Sign-in page text – this text is shown below the text box where an end user provides their credentials. It can be, for example, a welcome message for any user that signs in to your Microsoft 365 services.
Self-service password reset – this settings’ group lets you enable/disable password reset links shown under the credentials input box. You can change the default ‘Can’t access your account?’ and ‘Forgot my password’ texts, as well as customize the target URL of the self-service password reset page

On the last tab, you can check all the customizations you’ve done so far. To apply your configuration, click Save.

You can additionally customize the appearance of the Microsoft 365 sign-in page, depending on language detected by a web browser.

To do it, select the Browser language customizations tab (on the main Company Branding settings page) and click the Add browser language button. Next, choose a language from a drop-down list and configure the same settings as above, changing, for example, texts (Username hint text, Sign-in page text) to appear in the selected language. Note that the language-specific sign-in experience will override the default one, once the language is detected by a user’s web browser.

Below you can see the customized sign-in page examples: using the standard settings (top image) and using a custom CSS file (bottom image). Note that these settings don’t apply when you sign in to the Microsoft Entra admin center and Azure Portal.

The second thing that you can brand in Microsoft 365 are apps like:

Outlook on the web (OWA),
Microsoft Bookings,
Viva Engage,
SharePoint.

Most changes you can apply are limited to the app header (but not only). The header is that bar you can see at the very top of your browser window that shows service’s name and your user avatar, among other things.

To start the customization, sign in to the Microsoft 365 admin center and navigate to Settings > Org settings > Organization profile > Custom themes.

In the pane that opens, you can either modify the default theme or create your own one and assign it to up to 5 Microsoft 365 groups. Let’s go for the second option, as it covers all settings from option no. 1 and some additional ones.

To start, click the Add theme button.

This first tab lets you specify the basics of your theme:

Name – a self-explanatory setting allowing you to define name for your custom theme.
Groups – this one lets you specify the scope of users to whom the theme will be applied. You can do it by typing Microsoft 365 groups names in the text box provided, and the maximum number of them is 5.
Prevent users from overriding their theme – if you enable this checkbox, users with the custom theme won’t be able to change it to any different one by using the cogwheel (Settings) icon on the header. The only exception are the high-contrast themes, which will still be available to choose.
Show the user’s display name – by default, only user’s avatar is shown on the very right-hand side of the header. With this option selected, user’s display name will also be shown on the header, next to user’s avatar.

The tab’s name speaks for itself – here you can add your organization’s logo that’s going to be displayed on the header between the app launcher (on the far-left side) and a given service’s name. The only way to do it is by uploading your company logo in the JPG, PNG, GIF or SVG format to a secure web location (HTTPS), and then providing the image link in the Default Logo section. Once you provide the link, the logo preview on the header is shown automatically.

Because Microsoft 365 will always scale your logo, it’s reasonable to ask your graphic designer to add a little bit of padding (outer spacing) to it, so that it doesn’t blend with the header outer edges.

If your logo doesn’t fit dark themes well, you’ll also need to have its different version prepared and then provide the address where you host the image in the Alternate Logo section.

With the On-click link option, you can add a link to your logo, for example, to let users easily access your organization’s website.

Using the settings on the last tab, you can specify colors for three elements:

Header
Texts and icons on the header
Color of accented interactive elements on the header (e.g. icons when hovered on) and in a service’s window (e.g. ‘New mail’ button in Outlook on the web, tab marker In Viva Engage, etc.).

Similar to the sign-in page settings, the colors can be defined based on Hex and RGB values. What’s more, Microsoft’s algorithms will automatically check if the colors you provided are contrastive enough to serve people with disabilities.

Finally, if you don’t like the custom colors you’ve defined, you can quickly go back to the defaults by clicking Reset Colors.

Below you can see the customization in action. Take note of the following changes:

Custom company logo on the header
Custom color of the header
Custom accent color: header icons when hovering mouse cursor over it, buttons (New private message), selected tab marker (Unread, Private messages, All)
User’s name displayed next to the avatar in the top right corner
Possibility to choose only the custom theme or a High Contrast theme in the Settings pane