After going undrafted in the 2007 NBA draft, Calloway joined Fort Wayne Mad Ants of the NBA Development League. He led his team in scoring with 19 points per game and was sixth in the league with 5.8 assists and fourth with 2.1 steals per game. He also contributed 5.1 rebounds per game and was named team MVP at the end of the season.
On August 3, 2009, Calloway joined Cajasol on a one-year deal.[2] In his first season with Cajasol, he averaged 9.4 points and 4.2 assists in 36 Spanish League games. On July 23, 2010, he extended his contract until the end of the 2011–12 season.[3]
On June 24, 2020, he has signed with Rouen Métropole Basket of the French Pro B.[9] However, on August 16 it was announced that he was suffering from a knee problem and would not join the team.[10]
In the summers of 2016 and 2017, Calloway played in The Basketball Tournament on ESPN for team Trained To Go. He competed for the $2 million prize, and in 2016, averaged 5.3 points per game. In 2017, Calloway and team Trained To Go lost in the first round of the tournament to the Broad Street Brawlers 108–95.[12]