Federer wrote Friday on Twitter that he is "really excited" about the pairing and posted a photo of the two tennis stars from what he said was 15 years ago.
Federer is 34, Hingis is 35.
Federer owns a record 17 Grand Slam singles titles. He also owns two Olympic medals: silver in singles at London in 2012, and gold in doubles with Stan Wawrinka at Beijing in 2008. Rollback the years with @mhingis. Really excited to be playing mixed doubles with you 15yrs later at the Rio games ~ Roger Federer Twitter
Hingis owns 20 major titles -- five in singles, 11 in women's doubles, four in mixed doubles -- and is a member of the International Tennis Hall of Fame. She retired from singles but still competes in doubles, winning women's and mixed titles at the U.S. Open in September.