King revealed the move only hours after the Nets fell to the injury-depleted Chicago Bulls in Game 7 of their Eastern Conference quarterfinal playoff series at Barclays Center.
Carlesimo was tapped Dec. 27 to replace the fired Avery Johnson and led the Nets to 35-19 record over the final 54 games of the season.
"The Brooklyn Nets organization would like to thank P.J. for his efforts with the team in his roles as both head coach and assistant, and for his contributions to the team's success both on and off the court," King said in a statement. "We wish P.J. and his family only the best in the years to come."
The 63-year-old NBA veteran coach was released despite steering the Nets into the playoffs for the first time since 2007.
Carlesimo sports a 239-315 lifetime NBA coaching record, but is just 6-13 in the post-season and has not won a playoff series.