In his first full season with the Knights, having arrived in Vegas on February 19, 2020 (8 points in 10 games), Martinez established himself as a mainstay on the blue line, forming one of the best pairs in the league with
Alex Pietrangelo. In the end, Martinez collected a total of 32 points, including nine goals, in 53 regular games. In the playoffs, he collected six points in 19 games.