Cambridge United head coach has been sacked less than three weeks after their derby day mauling at Peterborough United.
The Cambridge board reacted to a defeat that left the club just four points and three places above the relegation zone by dismissing Bonner on Wednesday morning.
Bonner (38) was one of the youngest managers in the EFL. He was promoted from the club’s Academy to become Cambridge first-team boss in 2020 and steered them to promotion from League Two before keeping them up on the final day of the League One season last term, helped by a 2-0 win at home to Posh in April.
Cambridge also won an FA Cup tie at Newcastle United in Bonner’s time.
Cambridge owner Paul Barry said: “Mark Bonner will rightly go down as one of the most important people in the history of Cambridge United Football Club.
"All of us - owners, board, staff, players and fans - know how lucky we have been to have him and how hard this decision has been.
“Cambridge United has made huge strides on and off the pitch over the last five years and Mark has been instrumental in building our strong foundations for the future, creating special memories and moments for all of us along the way - most notably promotion during lockdown, Newcastle away in the FA Cup and the great escape last season.
“He has done it through his leadership and energy, his talent as a coach, his natural communication and empathy, and his desire to push the club forward on and off the pitch as someone born and brought up in Cambridge, who genuinely cares about our city and its communities.
"But in football, sometimes you do have to make decisions you believe are right for the long-term future of the club - difficult though they can sometimes be.
“Given our recent performances and results, we all feel - owners and board - that this is the right moment to part company with Mark, with huge respect, admiration and acknowledgement for all we have achieved together.
“We will now consider the right appointment for the club at this stage of our development. In the meantime, Barry Corr, working with Kevin Betsy will have responsibility for the first team squad.”