Bishop John Satterthwaite, 89, was staying at The Lodge care home, a part of the Buckshaw Village Retirement complex in Chorley, Lancashire.
It was there that Kate Rogowski, 25, slapped Rt Rev Satterthwaite on the bottom. She also made Mr Satterthwaite, who suffered from dementia, take cold showers.
Mr Satterthwaite died a month before Rogowski's abuse came to light. Her abuse did not cause Mr Sattherthwaite's death. It's thought a colleague of Rogowski's raised concerns she was abusing him.
The magistrates bench in Preston Magistrates Court said Ms Rogowski "acted in direct contravention of his care plan, causing him unnecessary humiliation and degradation by cold showering him and slapping his bottom".
Magistrates also said Rogowski had shown no remorse for her actions.
Rt Rev John Satterthwaite was the Bishop of Gibraltar and the Bishop of Fulham from 1980 to 1993.
He was the General Secretary of the Church of England's Council for Foreign Relations between 1955 and 1970.
The Diocese of Carlisle, where he came from, and the Diocese of Blackburn said in a joint statement after the magistrate's ruling: "We are really shocked to discover this sad end to the very distinguished life of Bishop John.
"He was a tremendous character with a huge fund of interesting stories about his time as Bishop of Europe. He was an ardent ecumenist with excellent links with sister churches.
"Bishop John was much loved by the very many people who knew him. All people deserve respect, but especially the most vulnerable in our society. We pray for all those who work for older people."
A spokesman for HICA, which manages The Lodge care home, said: "We are gravely saddened for the resident that this situation occurred and we appreciate how distressing this is for the person and their family members and the team currently working at the home.
"At HICA we have a zero tolerance approach to any forms of abuse and our safeguarding policy and training ensures that any issues such as these are reported immediately and action taken.
"As a not-for-profit organisation our only objective is to provide, safe, caring, responsive, effective and well-led care services and we are proud to be working with both safeguarding departments and the police across all areas of our operation to ensure that poor practice such as this is stamped out in the care sector."