Gloucester City councillors voted to remove Jeremy Hilton as leader following claims of financial mismanagement and a lack of transparency.
Hilton had led a Liberal Democrat minority administration since the party became the largest group on the council after the May 2024 elections.
The motion was submitted by councillor Alastair Chambers, who said the authority needed change.
Hilton declined to comment after the vote.
Gloucester Liberal Democrats criticised the move, saying opposition councillors had removed the leader without setting out an alternative administration, leader or plan.