A league source told NFL Network insider Jason La Canfora that Martz walked into Bears coach Lovie Smith's office Tuesday morning and announced that he didn't intend to come back because of philosophical differences over how the team could run its offense.
Quarterbacks coach Shane Day also will not return.
"After meeting with Mike this afternoon, we both felt it was best to move in different directions," Smith said in a statement released by the team. "I appreciate the job he and Shane did for us over the last two years."
There had been rampant speculation as the season dragged on that Martz, who had an expiring contract, could be done in Chicago. Smith was noncommittal when asked Monday during his end-of-year news conference if he would retain Martz, who was the mastermind of "The Greatest Show On Turf" as the St. Louis Rams' offensive coordinator and coach.
Monday's changes come after the Bears finished the season 8-8 following a collapse marked by season-ending injuries to quarterback Jay Cutler and running back Matt Forte, along with the arrest of backup wide receiver Sam Hurd on federal drug charges.
Caleb Hanie struggled in a big way filling in for Cutler, going 0-4 as the starter before Josh McCown received the nod. There were costly mistakes by backup running back Marion Barber in back-to-back close losses to the Kansas City Chiefs and Denver Broncos. Roy Williams also dropped a sure touchdown pass in that seven-point loss to the Chiefs.
Now Smith is looking for his fourth offensive coordinator as he prepares for his ninth season as the Bears' coach. Offensive line coach Mike Tice might be first in line for an interview, even though he has never been an offensive coordinator. He was heavily involved with the offense as the Minnesota Vikings' coach for four seasons.
The Associated Press contributed to this report.