Cook went unclaimed in the 2019 NBA Draft, but he was able to catch on with the Nuggets prior to the season via a two-way contract. But the Nuggets waived Cook in mid-October and he was claimed off waivers by the Cavaliers. Cook then played in 11 games off the bench for Cleveland, averaging 1.7 points and 0.9 rebounds in 3.2 minutes per game. Cook was waived by Cleveland in early January, but the signed back-to-back 10-day contracts with with the Cavs. On Feb. 17, while with Cleveland's G League squad, the Canton Charge, he was traded to the G League Oklahoma City Blue. Then, on June 30th, Cook signed a two-way contract with the Nuggets while the league was on pause for the coronavirus pandemic. He went on to appear in two games for Denver during the Orlando bubble, averaging 2.0 points, 2.0 rebounds and 1.0 steals in 9.5 minutes. His playing time was significantly more plentiful in the G League, where he appeared in 29 games split between the Canton Charge and Oklahoma City Blue, averaging 12.9 points with 5.7 rebounds on 58.2 percent shooting. At the NBA level, Cook scored a season-high four points on three separate occasions. One of those games came Aug. 14 with the Nuggets, when he added four rebounds and two steals -- both season highs. Cook made his NBA playoff debut in Game 2 of the first round against Houston, pulling down two rebounds in just over four minutes.