The former couple, together with the cast of the Vampire Diaries series, were present at the celebration for the 100th episode of the CW series on Saturday in Atlanta.
Dobrev, 24, had a short fling with “Dancing with the Stars” performer Derek Hough, but they broke up after just six weeks.
Ian, 34, and Nina’s relationship ended on good terms, with the two remaining close friends.
“There’s no bad blood between them,” a source told E! Online at the time of their breakup. “There was no other person involved or any big fight.”