The animal, called Bud, was punched during violent confrontations between Newcastle United and Sunderland fans in Newcastle April 2013.
A 45-year-old man was later jailed for a year after admitting violent disorder.
Bud was quickly back on duty with West Yorkshire Police’s mounted section.
But the force said he was now leaving the county to take a position with the Metropolitan Police’s horse unit.
A spokesman said: “Bud, now aged 15, is coming towards the end of his working life, but with his many years’ experience, he will be taking a lead role in assisting to train new horses as part of the Met’s mounted section.”
Bud’s departure coincides with the retirement of another horse called Louis, who has served the West Yorkshire force for 16 years and was nicknamed ‘Warrior’ following his role during the Bradford riots.