On March 9, 2017, Uthoff signed a 10-day contract with the Dallas Mavericks.
He made his NBA debut the following day in the Mavericks' 105–96 win over the Brooklyn Nets, playing two minutes. On March 19, 2017, he signed a second 10-day contract with the Mavericks. During his first 20 days as a Maverick, he received two assignments to the Texas Legends and then on March 29, 2017, he signed a multi-year contract with the Mavericks.
He played in nine games with Dallas, averaging 4.4 points and 2.6 rebounds per game.