In this blog post, I will show you how to add your company logo to Office 365 so when your user’s login to Office 365 they can see your branding.
To perform this task, you need to be Global Administrator in your Office 365 tenant.
You start, by login into the Office 365 Admin Center.
From the left menu click on:
From the Organization profile page click on Edit next to Manage custom themes for your organization
In the Customize Office 365 for your organization using the Upload button to upload your branding