It's the first revamp for the software in several years and comes as AOL tries to revitalize its business and compete with chat services on sites like Facebook and Google.
Among the new features is the ability to view pictures and videos inside chat windows. It also syncs messages across devices so messages aren't missed.
And its iconic "Buddy List" has given way to a list of AIM friends ordered by how recently you've chatted with them.
AIM is now the third most popular messaging service behind Yahoo Messenger and Windows Live Messenger.
The Associated Press contributed to this report.