Your Office 365 tenant ID is a globally unique identifier (GUID) that is different than your tenant name or domain. On rare occasion, you might need this identifier, such as when configuring Windows group policy for OneDrive for Business.
If you do need to find your Office 365 tenant ID, it's pretty easy. Choose one of the following procedures.
Use the Azure AD portal
Office 365 uses Azure AD to manage user accounts.
You can find your tenant ID in the Azure AD portal. You'll need to be an Azure AD administrator.To find your Office 365 tenant ID in the Azure AD portal
Log in to Azure AD as an administrator.
(You can reach Azure AD from the Office 365 Admin center by selecting Azure AD on the Admin centers list.)
In the Azure AD portal, click Active Directory.
In the Active Directory list, click the directory that you're using with your Office 365 tenant.
The tenant id for your Office 365 tenant is displayed as part of the URL:
Use Windows PowerShell
You can use Windows PowerShell to find the tenant ID. You'll need the Microsoft Azure PowerShell module.
Open a Microsoft Azure PowerShell command window and run the following script, entering your Office 365 credentials when prompted.
Your tenant ID is listed in the output.