After going undrafted in the 2015 NBA draft, Sykes joined the Cleveland Cavaliers for the 2015 NBA Summer League. On September 28, 2015, he signed with the San Antonio Spurs, only to be waived by the team on October 21 after appearing in three preseason games. Nine days later, he was acquired by the Austin Spurs of the NBA Development League as an affiliate player of San Antonio.