He made his professional debut in the Turkish Second Division with Pertevniyal, Efes Pilsen's feeder club, during the 2007–08 season.

He was loaned to Antalya BB for the 2011–12 season, where he averaged 11.8 points, 1.9 rebounds, and 1.0 assists per game in the top-tier level Turkish League.

In August 2013, Mahmutoğlu signed a two-year contract with an option to extend it for one more season, with Fenerbahçe.

[3] Before the start of the 2015–16 season, he was named the team's captain, after departure of Emir Preldžić.

He also played for the Turkish national team, and won the gold medal, at the 2013 Mediterranean Games.