No terms were disclosed.
The 6-foot-5 inch, 202-pound Ager was the 28th overall selection in the draft.
In his senior campaign at Michigan State, he averaged 19.3 points per game and was named Second Team All-Big Ten.
Ager finished 11th in career scoring at MSU with 1,554 points, was fourth in three-point field goals made (202) and third in three-point field goals attempted (532).
"We are excited about taking Maurice Ager with our late first-round pick," said Coach Avery Johnson on the Mavericks' Web site. "He was a four-year player at Michigan State for Tom Izzo and improved every year. He fits into our system and fills a need for us as a guard who can play tough defense and solid offense."