The move was announced by president of baseball operations Michael Hill just minutes after the Marlins were almost no-hit by Atlanta right-hander Shelby Miller in a 6-0 loss, which gave the Braves their second three-game sweep in Miami this season.
Hill also announced that bench coach Rob Leary had been fired and said the team was seeking consistency.
"We haven't played to our capabilities and we're hopeful that a new voice will spark and motivate our guys to get them going," Hill said.
Redmond, a former catcher for the Marlins, was hired as manager in November 2012 and went 155-207 in his two-plus seasons. He signed an extension last offseason that was to last through the 2017 season.