SharePoint Online: PowerShell to Add User to Group

Requirement: Add user to group in SharePoint online using PowerShell.

Prerequisites: You need to have SharePoint Online Management Shell installed in your client machine!

How to Add Members to a SharePoint Online Group?
To provide access to your SharePoint Online site, you can add users to SharePoint Groups such as the default groups - Site Owners, Site Members or Site Visitors. Here is how to add members to SharePoint group:

• Log in to the SharePoint Online site which you wish to add members, as an administrator.
• On the site's home page, Click the Settings gear icon >> Choose Site permissions >> and then Click on "Advanced Permissions Settings". Alternatively, You can click on Settings >> Site Settings >> "Users and Permissions" link under "People and Groups" from any where else in the site.
• A list of SharePoint groups appears. Click on the name of the group >> Once the desired group has been chosen, click on "New" button in the toolbar and then choose "Add Users" to add users to the group.
  
• In the Add users window, Enter the user's email address or username and click on "Share" button.
  

The user will now be added within the specified group!

SharePoint Online PowerShell to Add User to Group
To add an individual user to SharePoint online site collection group using PowerShell, use Add-SPOUser cmdlet from SharePoint online management shell. Here is an example:

Step 1: Enter the connection Credentials for SharePoint Online Admin Center

$Credential = Get-credential

This prompts for user name and password. Key-in your SharePoint online Administrator credentials.

Step 2: Connect to SharePoint Online Service:

Connect-SPOService -url https://Crescent-admin.sharepoint.com -Credential $Credential

Step 3: Add User to SharePoint Online Site Group:
Once the connection is established successfully in the previous step, you can add user to group.

Add-SPOUser -Site "https://Crescent.sharepoint.com/sites/Sales" -Group "Sales Members" -LoginName [email protected]

The SharePoint Online Management Shell looks like this:

This adds the given user to the group in SharePoint Online.
 
Bulk Add Users from a CSV File to SharePoint Online Group using PowerShell:
Now the next question is, What if you want to add 100's of users to a site collection? Here is how to add multiple users to groups in SharePoint online from a CSV file.

Step 1: Create a CSV file and fill in according to your requirements

Step 2: Use this PowerShell script to Read from CSV and import users to SharePoint Group:

#Connection paramaters
$AdminURL = "https://Crescent-admin.sharepoint.com/"
$AdminName = "[email protected]"
$CSVFile="C:\UsersToAdd.csv"

#User Names Password to connect 
$Password = Read-host -assecurestring "Enter Password for $AdminName" 
$Credential = new-object -typename System.Management.Automation.PSCredential -argumentlist $AdminName, $Password

#Connect to SharePoint Online
Connect-SPOService -url $AdminURL -credential $Credential

#add multiple users to sharepoint online group powershell - Import Users from CSV
Import-Csv $CSVFile | ForEach-Object { Add-SPOUser -Site $_.SiteURL -Group $_.GroupName -LoginName $_.UserAccount}

You can also use CSOM PowerShell to add user to group. Here is how: SharePoint Online: Add user to group using PowerShell CSOM

PnP PowerShell to Bulk Add Multiple Users to Multiple Site's Group in SharePoint Online:
Here is an another case: How to add multiple users to multiple site collection's Owners group?

#Variables
$SiteURLs = "Sales","Intranet","Marketing" 
$UserIDs = "[email protected]","[email protected]"

#Iterate through each site
ForEach($Site in $SiteURLs)
{
    #Connect to SharePoint Online Site
    Write-host "Connecting to Site: "$Site
    Connect-PnPOnline -Url https://crescent.sharepoint.com/sites/$Site -UseWebLogin

    #Get the Associcated Owners group of the site
    $Web = Get-PnPWeb
    $Group = Get-PnPGroup -AssociatedOwnerGroup

    #Add Each user to the Group
    ForEach($User in $UserIDs)
    {
        Add-PnPUserToGroup -LoginName $User -Identity $Group
        Write-host -f Green "`tAdded $User to $($Group.Title)"
    }
}