General manager Billy King announced the move Thursday without saying who will be interim coach. The Nets next play at home Friday against Charlotte.
Brooklyn started the season 11-4, winning five in a row to end November. But the team has been in a spiral since and is now 14-14. The Nets lost to Milwaukee 108-93 on Wednesday night. They also have dropped two games to the crosstown Knicks.
Johnson has been the Nets' coach for a little more than two seasons. He went 60-116 with the Nets, who moved from New Jersey to Brooklyn to start the 2012-13 season. Johnson coached the Dallas Mavericks to an appearance in the NBA Finals in 2006.