Tigers chairman Assem Allam has backed the verdict of vice-chairman and son Ehab Allam to dispose of Barmby's services earlier this month. Barmby was initially suspended on April 30 over comments made about the npower Championship club's finances and a lack of funds made available to strengthen during the January transfer window.
It was announced on May 8 that Barmby had been sacked after six months in charge of his hometown outfit, a decision the 38-year-old subsequently appealed. But that has been rejected by Assem Allam following a hearing between him and Barmby.
A full statement from Assem Allam on the Hull Daily Mail website read: "Having heard Nick Barmby's internal appeal and following a full review of the facts during a detailed and thorough meeting with him, I have decided to uphold the vice chairman's decision to dismiss Nick for the reasons previously stated.
"I would like to assure the club's supporters that this decision has not been taken lightly and all other options were explored before I decided to uphold the dismissal.
"However, as explained in the press statement given by the vice chairman, Nick's behaviour has led to the breakdown of trust and confidence with the board and I therefore felt I had no other option particularly given his senior position at the club.
"Nick was a fantastic player for the club and a local hero to the club's supporters. It is an extremely unfortunate end to a great period with the club although the club would like the supporters to remember Nick for his playing career and the part he played in the club's promotions."
Barmby first joined Hull as a player in 2004 and combined that with a coaching role at the KC Stadium in 2010 under then boss Nigel Pearson.
The former England striker took over as player/caretaker manager in November 2011 following Pearson's move to Leicester, announcing his retirement from the professional game in January before taking the reins on a permanent basis later that month.
Former Sunderland boss Steve Bruce is firm favourite to now replace Barmby.