SharePoint Online: Get Site Owner using PowerShell

Requirement: Get SharePoint Online Site Owner using PowerShell

How to Identify Site Owner in SharePoint Online?
You can find site owner SharePoint Online from SharePoint Online Admin Center.

• Sign in to SharePoint Online Admin Center (https://YourDomain-admin.sharepoint.com/_layouts/15/online/SiteCollections.aspx)
• Select the site collection you wish to get site owner from the site collections list >> From the ribbon, Click on "Owners" and then "Manage Administrators. 
• On the "Manage Administrators" dialog box, You'll get the site owner or primary site collection administrator.
  

Similarly, in modern admin center, You can navigate to: Sites >> Active Sites >> Select the site collection to get its owners >> Click on "Permissions" >> Click on "Manage Admins"
  
Let's see the PowerShell script to get SharePoint Online site owners.

PowerShell to Get Site Owner in SharePoint Online:
Here is the SharePoint Online PowerShell to list site owners

#Variables for Admin Center & Site Collection URL
$AdminCenterURL = "https://crescenttech-admin.sharepoint.com/"
$SiteURL = "https://crescenttech.sharepoint.com/sites/marketing"

#Connect to SharePoint Online
Connect-SPOService -url $AdminCenterURL -Credential (Get-Credential)

#sharepoint online powershell get site owner
Get-SPOSite $SiteURL | Select Owner

Get Site Owner in SharePoint Online using PowerShell
Here is how to get site owners of all SharePoint Online sites.

$AdminCenterURL = "https://crescenttech-admin.sharepoint.com/"

#Connect to SharePoint Online
Connect-SPOService -url $AdminCenterURL -Credential (Get-Credential)

#Get Site owners of all site collections
Get-SPOSite -limit ALL | Select URL, Owner

This PowerShell script retrieves site owners from all site collections. If you want to change site owner, use: How to Change Site Owner in SharePoint Online using PowerShell?

You can export Site Owners information to CSV file as:

Get-SPOSite | Select URL, Owner | Export-CSV "C:\Temp\SiteOwners.CSV"

Get Site Owners of Office 365 Group Connected Sites
While the above scripts works fine with sites without Office 365 groups, We got to change the script a bit to get site owners of a Office 365 group connected site collections, as the site owners is set as group owner.

Import-Module Microsoft.Online.SharePoint.PowerShell
Import-Module AzureAD

#Variables for Admin Center & Site Collection URL
$AdminCenterURL = "https://crescent-admin.sharepoint.com/"
$SiteURL = "https://crescent.sharepoint.com/sites/purchase"

#Get Credentials to connect
$Cred = Get-Credential

#Connect to SharePoint Online and Azure AD
Connect-SPOService -url $AdminCenterURL -Credential $Cred
Connect-AzureAD -Credential $Cred | Out-Null
 
#Get the Site Collection
$Site = Get-SPOSite $SiteURL

#Get Group Owners
$GroupOwners = (Get-AzureADGroupOwner -ObjectId $Site.GroupID | Select -ExpandProperty UserPrincipalName) -join "; "

Write-host $GroupOwners

This script retrieves all owners of the associated Office 365 group. Let's combine above and get site owners for all sites in the tenant:

#Variables for Admin Center
$AdminCenterURL = "https://crescentintranet-admin.sharepoint.com"
$CSVPath = "C:\Temp\SiteOwners.csv"
 
#Get Credentials to connect
$Cred = Get-Credential

#Connect to SharePoint Online and Azure AD
Connect-SPOService -url $AdminCenterURL -Credential $Cred
Connect-AzureAD -Credential $Cred | Out-Null
  
#Get all Site Collections
$Sites = Get-SPOSite -Limit ALL

$SiteOwners = @()
#Get Site Owners for each site collection
$Sites | ForEach-Object {
    If($_.Template -like 'GROUP*')
    {
        $Site = Get-SPOSite -Identity $_.URL
        #Get Group Owners
        $GroupOwners = (Get-AzureADGroupOwner -ObjectId $Site.GroupID | Select -ExpandProperty UserPrincipalName) -join "; "       
    }
    Else
    {
        $GroupOwners = $_.Owner
    }
    #Collect Data
    $SiteOwners += New-Object PSObject -Property @{
    'Site Title' = $_.Title
    'URL' = $_.Url
    'Owner(s)' = $GroupOwners
    }
}
#Get Site Owners
$SiteOwners

#Export Site Owners report to CSV
$SiteOwners | Export-Csv -path $CSVPath -NoTypeInformation

The site owner is automatically added as Site collection administrator of the site. If you want to get all site collection administrators, use: SharePoint Online: Get Site Collection Administrators using PowerShell