Manager Steve Evans left Peterborough shortly after their goalless draw with Charlton in Sky Bet League One on Saturday.
The club released a statement shortly after the game saying: "The football club wishes to announce that the manager Steve Evans and Assistant Manager Paul Raynor have been released from their contracts with immediate effect.
"We would like to thank both Steve and Paul for their efforts on behalf of the football club. We wish them and their families all the best for the future."
Peterborough had goalkeeper Conor O'Malley to thank as he dived low to his right in the 79th minute to keep out a poor penalty from Karlan Grant after Jason Naismith had needlessly slid in on Josh Cullen.
The penalty save was the big moment in a match of few chances between two sides in the play-off positions.
The Addicks had won three and drawn one of their past four matches, and after soaking up some early pressure Cullen tested O'Malley with a volley which the goalkeeper tipped over.
A minute into the second half Posh could have scored when Ivan Toney crossed low to Matt Godden, but his striker partner shot wide
Grant, who has been linked away with a move away from the club, then saw a deflected shot from the left-hand side of the penalty area hit the bar and bounce clear.
The striker should then have won the match, only for O'Malley to deny him from the spot.