Add a Site Collection administrator to all Site Collections in a Tenant (including OneDrive for Business sites)

I have come across this scenario many times where even if I am the tenant admin in my SharePoint Online tenant, it is not necessary that I will be the site collection admin of every site collection by default. This is by design and makes perfect sense as there might be some site collections where sensitive data might be stored and I might not have rights to see that data despite being the tenant admin. However, in some scenarios you might feel the need to give a user site collection admin rights for all the site collections in the tenant.

Also for OneDrive for Business site collections in the tenant, the user who is owner of the site collection is the only person who has site collection admin rights on it by default. This can be a problem for compliance and e-discovery reasons. You might be in a situation where you need to give site collection admin rights to a compliance manager or a global administrator on all the OneDrive for Business sites in a tenant.

In this post, lets have a look at how you can make a user a site collection admin on all the site collections in a tenant as well as on all the OneDrive for Business site collections in the tenant.

Some notes:

1) For now, this only works with SharePoint Online/Office 365.
2) You will need the SharePoint Online Client Side Object Model Nuget package
3) By changing a parameter in the SetSiteAdmin function, you can also remove a user from the site collection admins of all site collections.
4) The user who runs this code will need Tenant Administrator rights on the Tenant.

1) Add a site collection admin to all site collections in a tenant:

This is the easy part, all you need to do it get the urls of the site collections in the tenant and add the desired user as a site collection admin to it using the Tenant.SetSiteAdmin function.

2) Add a site collection admin to all the OneDrive for Business site collections in a tenant:

This takes a bit more work. Here are all the things we need to do:

1) Get the account names of the users in a tenant using People Search. Now bear in mind that search has a limitation of returning a maximum of 500 rows on SharePoint Online. That will be 500 users in our case. So if your tenant as more than 500 users, you will need to call search in batches of 500 to get the account names of all the users.

2) Once we have the account names of the users, we need to get the url of their OneDrive for Business sites. We can do this by querying the CSOM UserProfile API

3) After getting the OneDrive for Business site urls, all we need to do is use the same Tenant.SetSiteAdmin function as above.

Here is the complete code for that:


There is also another way to do the same thing where you get the OneDrive for Business site urls from the UserProfileService.asmx and then use the Set-SPOUser SharePoint Online PowerShell cmdlet to set the user as the site collection admin. Here are the details for that https://technet.microsoft.com/en-us/library/dn765092.aspx

Hope you found this article useful!