The U’s confirmed Buckingham’s departure on Sunday afternoon following a run of just one win in 15 games.
Oxford are currently 20th in the table, a point outside the relegation positions, and lost 3-1 at home to Sheffield Wednesday on Saturday.
A statement from the club read: “Oxford United can confirm that Des Buckingham has left his role as Men’s First Team Head Coach.
“Des was appointed in November 2023 and led the Club to promotion to the EFL Sky Bet Championship at the end of the 2023/24 season.
“The Club would like to place on record its thanks to Des for everything he has done during his time with us and wish him well for the future.
“The appointment of a new head coach will be confirmed in due course.”
Buckingham’s first home game in charge of Oxford was against Bolton in November last year and his side were hammered 5-0 at the Toughsheet a few months later.
But he got revenge with a shock 2-0 win in the play-off final to lead his side to promotion at Bolton’s expense.
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