Despite being defending gold medalists in the 4x200 at the 2019 World Relay Championships, the Brown and the Canadian relay team failed to advance out of the heats in the 4x100 m relay, attributed in part to an awkward baton exchange from Gavin Smellie to Brown. Competing on the 2019 Diamond League, he won back-to-back gold medals in the 200 m at the Diamond League Shanghai and the BAUHAUS-galan in Stockholm. He ran a new personal best time of 19.95 in the 200 m at the Athletissima in Switzerland, and went on to win both the 100 and 200 m events at the Canadian Championships. Competing at the 2019 World Athletics Championships in Doha, Brown qualified for the finals of both the 100 and 200 m, finishing eighth and sixth. In a disappointing finish, the Canadian relay team did not advance to the 4x100 m final despite having the eighth-fastest overall time due to their running in the faster of the two heats.