MTV's cameras caught the "Break Free" singer holding hands with the rapper backstage at the Video Music Awards on Sunday after opening the show with a "Bang Bang." (An Instagram video clip shows Big Sean valiantly helping Grande back up after she briefly stumbles.)
Grande, 21, performed the new single with Nicki Minaj and Jessie J, picking up her first VMA for best pop video later in the night. She's also up for three other categories.
A rep for Grande did not immediately respond to a request for comment.
Big Sean, 26, was set to marry Glee's Naya Rivera before ending their engagement in April. (Rivera went on to wed longtime friend Ryan Dorsey three months later.)
Meanwhile, Grande dated Australian boy-bander Jai Brooks on and off over the last two years and was linked briefly to The Wanted's Nathan Sykes.