Payouts to lags have cost taxpayers more than £30million in the past six years.
Inmates got compensation for injuries, trips and falls, damaged property and delayed release.
They also claimed for a lack of basic rights such as daily exercise, the Prison Officers’ Association said.
The union’s Mick Pimblett blamed the huge compo bill on a Tory failure to tackle the jail staffing crisis.
He said: “Due to poor pay and recruitment and retention, there are too few staff, which leads to prisoners not getting their entitlements required by law. This then leads to frustration that can lead to violence.”
Compo payouts peaked in 2019/20 at £7.6m, with £5.3m given last year.
Figures show there were 20,872 assault incidents in jails in England and Wales in the year to September 2022 – up from 18,853 in just a year.
In 2021, double killer Lee Newell, 52, got an £85,000 payout after losing an eye in an assault at HMP Woodhill in Milton Keynes, Bucks, in 2014.
Judge Peter Marquand found that the Ministry of Justice was “in breach of its obligation to keep the claimant reasonably safe” and awarded Newell the damages.
The Ministry of Justice said it successfully defends two-thirds of cases brought by cons and ensures debts to victims and courts are paid before any payment to the offender.