Adding members to Office 365 Security Group via csv

Make sure you Connected to Exchange Online PowerShell

Connect-MsolService

You can get the object id of the group you are planning to add from Azure Active directory portal

CSV Sample – Double quotes is very important otherwise you may see undesirable additions.

Import-Csv users.csv |ForEach-Object {Add-MsolGroupMember -GroupObjectId 6e5db514-b162-4de4-ab93-3f1944ea4167 -GroupMemberType user -GroupMemberObjectId (Get-MsolUser -UserPrincipalName $_.userprincipalname).ObjectId}