PC Jason Charles, 30, went to see Gloucester play Connacht in a European Cup play-off.
Charles – whose brother, uncle and cousin have all played for Gloucester – told a disciplinary hearing he was providing “high visibility policing”.
But as the game went into extra time the PC failed to respond to a radio alert to a “grade one” call from a woman at a nearby address.
Charles was already on a final written warning for swearing at fellow officers after being evicted from a nightclub.
And as disciplinary proceedings were launched into the rugby incident he got drunk in a pub and smashed a glass with his fist.
Charles, who said problems in his career began in 2014 after he sprayed eight people with CS gas in a street brawl, claimed he had been victimised after making seven whistleblowing complaints.
He was dismissed after a two-day hearing found him guilty of misconduct by going to the rugby and gross misconduct for smashing the glass.
Charles was backed by Gloucestershire Police and Crime Panel member Mark Rees.
He said the PC followed his training when he went to the rugby “to interact” with the public.
Mr Rees told the hearing: “I accept Jason is not perfect. But he is honest, he is decent, he is motivated. If I thought he was a prat and shouldn’t be in the police I wouldn’t be here.”
Charles will appeal