How to Customize the Browser Theme for a Microsoft 365 Tenant

Use Corporate Colors and Logo

None of us likes to feel that we’re part of an anonymous crowd, all looking and behaving the same. When organizations sign up for a cloud service, they cede control over the scope of the service they receive, and they lose the ability to tailor how software works. In a nutshell, you get what the service provider delivers.

Which is why you might want to customize the default theme used for Office 365 browser apps to apply your choice of corporate colors and logo and generally make the apps appear a little less one size fits all. With a little up-front preparation and maybe some assistance from people who are good with colors, this is easily done.

Customizing Your Tenant’s Theme

To start, go to the Org settings section under Settings in the Microsoft 365 admin center and choose Custom themes. You’ll then have some options to change the appearance of the bar displayed at the top of browser apps.

The bar is made up of several components from the waffle menu on the far left-hand side to the avatar on the far right. The components you can customize are in the middle and comprise of your logo, the background image for the piece between the corporate logo and the settings (cogwheel icon etc.), the overall color for the bar, and the color used for the text and icons placed on the bar (Figure 1). You can also make the logo clickable (bring the user to another web page).

Custom theme settings for a Microsoft 365 tenant
Figure 1: Custom theme settings for a Microsoft 365 tenant

Things to Consider

Microsoft’s instructions about how to create a custom theme are helpful and don’t need to be repeated here. As I played with custom themes, some facts became apparent:

  • When Microsoft specifies an image size, they mean it. It took a few tries to upload a custom logo. All attempts were rebuffed until I used an image sized at precisely 200 x 30 pixels. 199 x 30 pixels didn’t work.
  • Microsoft recommends SVG files for the logo because the SharePoint Online mobile app won’t display other formats. If you don’t care about this then PNG or JPG work just fine.
  • If you make the logo clickable, it closes the current page and goes to the place you specify. It doesn’t seem to be possible to make the link open in a new tab or window.
  • Color choice is really important. A color palette picker is available to choose colors from (or you can input the hex value of a color). It’s easy to make a mess, so if you are color blind (like I am), get someone who isn’t to check your selections. Or even better, find out the hex values for the corporate approved colors and use those.
  • A tenant can only have one custom theme.

If you make a mess, it’s easy to revert to the default theme and start over by using the Remove custom theming button at the bottom of the theme settings.

Figure 2 shows the result of some quick customizations to create an Office 365 for IT Pros theme. In this case, I chose a red background image with a red navigation bar with white text and icons. It was enough to validate that it’s easy to create a custom theme. I’m sure people can create something more artistic than I managed.

Components of a custom theme
Figure 2: Components of a custom theme

Once saved, the custom theme will be picked up by the Office 365 browser apps. Well, most apps, as Teams will do its own thing.

Limiting Theme Choice

If you want to force people to use the custom theme, you can set this option in the settings (Figure 3).

Option to stop users overriding the corporate (custom) theme
Figure 3: Option to stop users overriding the corporate (custom) theme

With the setting in place, users won’t be able to select one of the many optional themes packaged with Office 365 (Figure 4) and will have to be content choosing between the custom theme and the default Office 365 high contrast theme. There’s no administrative method available to select a specific theme for users.

Browsing the optional themes available in Office 365
Figure 4: Browsing the optional themes available in Office 365

Limiting choice to a bland corporate theme and a high contract theme seems like a step too far. I can see why some people might consider it a good thing to eliminate themes like Cats and the splendidly named Super Sparkle Happy theme, but let’s give users the chance to express themselves, even if their personal choices might occasionally be doubtful.

2 Replies to “How to Customize the Browser Theme for a Microsoft 365 Tenant”

  1. Hello Tony,
    I know that on-prem is more and more passe, but do you know if the same (or something similar) is possible on the Exchange Server (say, 2019)?
    I mean the company’s logo on the left upper corner.
    There is a kind of guide regarding how to create/customize OWApp theme (, but there is no clear indication how to put such logo there.
    I’m going to give it some tests anyway, but maybe you happen to know it already.

    Thanks in advance

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