PC Robert Dovey - an officer with West Yorkshire Police - punched the man several times before deliberately putting him in the back of his police van so he could "give him a good hiding" on the way to custody following an incident in December 2017.
The officer, who has served with the force since 2004, denied the allegations against him stating "anyone in the same situation would have done the same" but a three-day misconduct hearing found the matters proven and he was sacked immediately for gross misconduct.
Matthew Holdcroft, acting for the appropriate authority, said: "The red mist descended and he wanted to take matters into his own hands.
"There is no criticism of you for being angry or upset because your partner and fellow colleagues had been assaulted but the criticism is for failing to have the professionalism to say 'I don't need to go there or do this'.
"He found himself in a situation that none of us want to be in but having placed himself there he has acted with no discipline whatsoever.
"It is plain to see he has breached the Standards of Professional Behaviour which results in gross misconduct."
He then jumped into the rear of a colleague's van where the prisoner was and "without any warning punched the man in his face with his right hand".
The panel heard he threw six or seven punches as his colleagues had to pull him away.
The officer told the panel he had hit the man once in self defence because he had tried to bite him.
He said: "My use of force was proportionate in the circumstances. This was someone that could have caused me serious injury. My behaviour was extremely reasonable given the circumstances and it was necessary.
"Anyone in that situation would have done the same as what I did."
The panel then heard how PC Dovey and his Sergeant were in the van transporting the prisoner to custody when PC Dovey said "we need to pull over somewhere quiet and give this guy a good hiding".
He said: "I said more than once that he deserved a good hiding, that is how I was feeling as I could not believe what he had done to the other officers. I admit it was not professional or rational but that was a difficult incident to deal with."
Following the evidence, PC Dovey was found to have breached the Standards of Professional Standards in relation to Use of Force, Authority Respect and Courtesy and Discreditable Conduct.
He was found to have used force that was not deemed reasonable, necessary or proportionate on a member of the public who had been detained by other officers
It was also proven that he had moved the prisoner into another van to give the officer the opportunity to assault him further during the transfer and during the journey.
He was dismissed without notice.