After going undrafted in the 2016 NBA draft, Ellis joined the Dallas Mavericks for the 2016 NBA Summer League. On September 23, 2016, he signed with the Charlotte Hornets, but was waived on October 22 after appearing in one preseason game. On October 31, 2016, he was acquired by the Greensboro Swarm of the NBA Development League as an affiliate player of the Hornets. Ellis appeared in all 50 games for Greensboro in 2016–17, averaging 9.8 points and 4.7 rebounds per game.