Ad Age first reported the news of the review in December, when Micorosft said they were conducting a closed review of its media account as part of its "normal course of business." Adweek reported the winner earlier Friday.
Microsoft awarded the work to Dentsu, with the win led by media agency Carat.
"After completing a review of our global media agencies, we are extending our relationship with Dentsu Aegis," Kathleen Hall, corporate VP of brand, advertising and research at Microsoft, said in an emailed statement.
In April 2014, Microsoft selected Interpublic Group as agency of record for advertising and global deployment and Dentsu Aegis Network to handle search advertising and media buying and planning — right on the heels of appointing Chris Capossela as its new chief marketing officer.
The Redmond, Washington-based tech company continues to work with m:united//McCann, a dedicated agency within IPG, for its creative work.