The Lakers announced the surprising move Friday, several hours before they hosted Golden State. Assistant coach Bernie Bickerstaff will coach the Lakers against the Warriors.
"This was a difficult and painful decision to make," Lakers general manager Mitch Kupchak said. "Mike was very hard-working and dedicated, but we felt it was in the best interest of the team to make a change at this time. We appreciate Mike's efforts and contributions and wish him and his family the best of luck."
Los Angeles' dismissal of Brown was first reported by USA Today Sports.
Los Angeles began the season with championship expectations after trading for center Dwight Howard and point guard Steve Nash, adding two superstars alongside Kobe Bryant and Pau Gasol.
But the Lakers went 0-8 during the preseason last month for the first time in franchise history before stumbling into the regular season with an 0-3 start, losing to Dallas, Portland and the Clippers. After finally beating Detroit last Sunday for their first win, the Lakers looked listless again in a loss at Utah on Wednesday. The Lakers' 1-4 record is the worst in the Western Conference.
While Lakers fans had reacted with their usual panic whenever the 16-time NBA champions lose a few games in a row, Kupchak and Lakers owner Jim Buss publicly appeared to stand firmly behind Brown, the longtime Cleveland Cavaliers coach hired to replace 11-time NBA champion Phil Jackson.
The Lakers had given no indication they might pull one of the earliest coaching changes in NBA history.
Los Angeles went 41-25 and reached the second round of the playoffs last season in Brown's debut, losing to Oklahoma City. Brown received criticism for that largely successful season, with Magic Johnson predicting Brown would be fired if the Lakers lost to Denver in the first round.
Brown implemented a new offensive scheme this fall that didn't appear to suit his players' talents, yet the Lakers also played spotty defense, Brown's specialty. The Princeton-based offense received ridicule, but Bryant and his teammates largely defended the motion scheme, saying they needed time to implement it.
Brown is a protégé of San Antonio coach Gregg Popovich. He led Cleveland to the 2007 NBA finals and went 272-138 with the Cavaliers, becoming the most successful coach in franchise history while compiling the league's best regular-season record in each of his last two seasons.