The move Monday was the second time the rookie guard has been assigned to the Texas Legends, who play in the Dallas suburb of Frisco. He averaged 18 points in seven games earlier this season.
Cunningham has played in eight games for the Mavericks, averaging two points and 3 minutes per game.
The Mavericks also added veteran guard Mike James for the rest of the season. Dallas either had to guarantee him the prorated amount of the $1.2 million veteran minimum or let him go after signing him to a pair of 10-day contracts.