The former Torquay United and Bristol Rovers boss was appointed as the replacement for long-serving manager Mark Yates in late November.
However, Buckle managed only one win in 13 matches and leaves Cheltenham just one point above the relegation zone.
"The board of Cheltenham Town FC have reached an agreement with manager Paul Buckle for him to leave the club," read a Cheltenham statement.
"Paul has departed from Cheltenham Town by mutual consent and with immediate effect.
"Head of academy coaching Russell Milton will take caretaker charge of the first team for Saturday's home match against Bury."
Cheltenham face Bury at home on Saturday.
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