SharePoint Online: PowerShell to Get All Site Collections and Subsites

Import-Module Microsoft.Online.SharePoint.Powershell

#Config Parameters
$AdminSiteURL="https://crescent-admin.sharepoint.com"

#Get Credentials to connect to SharePoint Admin Center
$Cred = Get-Credential

#Function to get all subsites of a site
Function Get-SPOWeb($WebURL)
{ 
    #Setup credentials to connect
    $Credentials = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($Cred.Username, $Cred.Password)

    #Get Web information and subsites
    $Context = New-Object Microsoft.SharePoint.Client.ClientContext($webURL)
    $Context.Credentials = $Credentials
    $Web = $context.Web
    $Context.Load($web)
    $Context.Load($web.Webs)
    $Context.executeQuery()
 
    #Iterate through each subsite in the current web
    foreach ($Subweb in $web.Webs)
    {
        #Get the web object
        $Subweb

        #Call the function recursively to process all subsites underneath the current web
        Get-SPOWeb($Subweb.url)
    }
}

#Connect to SharePoint Online Admin Center
Connect-SPOService -Url $AdminSiteURL -Credential $Cred

#Get All site collections
$SiteCollections = Get-SPOSite -Limit All

#Traverse through each site collection and get their subsits
Foreach ($Site in $SiteCollections)
{
    Write-Host $Site.Url     
    $AllWebs = Get-SPOWeb $Site.Url
    $AllWebs | ForEach-Object { Write-Host $_.URL }
}   

#Load SharePoint CSOM Assemblies
Add-Type -Path "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.dll"
Add-Type -Path "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.Runtime.dll"

#Function to get each subsite in site collection
Function Get-SPOWebs($SiteURL)
{
    $Credentials = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($Cred.Username, $Cred.Password)

    #Setup the context
    $Ctx = New-Object Microsoft.SharePoint.Client.ClientContext($SiteURL)
    $Ctx.Credentials = $Credentials

    #Get the web
    $Web = $Ctx.Web
    $Ctx.Load($Web)
    $Ctx.Load($Web.Webs)
    $Ctx.ExecuteQuery()

    #Do something
    Write-host $Web.Url

    #Loop through each each subsite in site
    Foreach($Web in $web.Webs)
    {
        Get-SPOWebs $Web.Url
    }
}

#Variables
$AdminCenterURL = "https://Crescent-admin.sharepoint.com"

#Setup Credentials to connect
$Cred= Get-Credential
 
#Connect to SharePoint Online
Connect-SPOService -url $AdminCenterURL -Credential ($Cred)

#Get all Site collections
$Sites = Get-SPOSite -Limit All

#Loop through site collections
ForEach($Site in $Sites)
{
    #Call the function to get all sub-sites in site collection
    Get-SPOWebs($Site.URL)
}

#Set Variables
$SiteURL = "https://crescent.sharepoint.com/"

#Get Credentials to connect
$Cred = Get-Credential

Try {
    #Connect to PnP Online
    Connect-PnPOnline -Url $SiteURL -Credentials $Cred

    #Get All Site collections  
    $SitesCollection = Get-PnPTenantSite

    #Loop through each site collection
    ForEach($Site in $SitesCollection)  
    {  
        Write-host -F Green $Site.Url  
        Try {
            #Connect to site collection
            Connect-PnPOnline -Url $Site.Url -Credentials $Cred

            #Get Site Collection administrators of the site
            $SubSites = Get-PnPSubWeb -Recurse
            ForEach ($web in $SubSites)
            {
                Write-host `t $Web.URL
            }
        }
        Catch {
            write-host -f Red "`tError:" $_.Exception.Message
        }
    }
}
Catch {
    write-host -f Red "Error:" $_.Exception.Message
}

#Parameters
$TenantAdminURL = "https://Crescent-Admin.SharePoint.com"
 
#Connect to Admin Center
$Cred = Get-Credential
Connect-PnPOnline -Url $TenantAdminURL -Credentials $Cred
 
#Get All Site collections - Exclude: Seach Center, Mysite Host, App Catalog, Content Type Hub, eDiscovery and Bot Sites
$SitesCollections = Get-PnPTenantSite | Where -Property Template -NotIn ("SRCHCEN#0", "SPSMSITEHOST#0", "APPCATALOG#0", "POINTPUBLISHINGHUB#0", "EDISC#0", "STS#-1")
 
#Loop through each site collection
$SubSitesData = @()
ForEach($Site in $SitesCollections)
{
    #Connect to site collection
    Write-host -f Yellow "Processing site:"$Site.Url    
    $SiteConn = Connect-PnPOnline -Url $Site.Url -Credentials $Cred
 
    #Get the SubSites of the site collection
    $Webs = Get-PnPSubWeb -Recurse -Connection $SiteConn

    #Collect Subsites count
    $SubSitesData += New-Object PSObject -Property ([ordered]@{
        SiteName = $Site.Title
        URL = $Site.URL
        SubSitesCount = $Webs.Length
    })
    
    Disconnect-PnPOnline -Connection $SiteConn
}
$SubSitesData