Cheeks was replaced on an interim basis by Kevin Pritchard, director of player personnel.
The Blazers have lost seven of their last nine games. They are 22-33 and in sixth place in the NBA's Western Conference.
Cheeks, who played in the NBA for 15 seasons, was hired to coach the Portland team June 27, 2001. His overall record was 162-139.
"We made this change in order to evaluate the entire roster and to put the franchise in the best position as we head towards the draft and free agency," General Manager John Nash said.
Portland likely will miss the playoffs for a second year in a row after 21 consecutive appearances.