Brimah spent the NBA G League Single Site season with the Mad Ants in 2021. While Brimah had been part of the organization the previous season, an injury prevented him from playing with the Mad Ants.
After missing the full 2019-20 season due to injury, Brimah joined the Mad Ants for the single site season in Orlando this February. Playing in 10 games with the Mad Ants, Brimah ranked second in the NBA G League in blocks per game (2.8) and was third in overall blocks (28) during the season. His defensive efforts moved him into sixth all-time in NBA G League blocks with 297 in his career.
Brimah became the 20th overall NBA Call-Up in Mad Ants history on April 23, 2021 when he signed a two-way contract with the Indiana Pacers.
Brimah played in five games with the Pacers, averaging 2.6 points and 1.6 rebounds per game.