Diana Turner, 53, used the money to buy houses, holidays and high-performance cars over a 10-year period, South Yorkshire Police said.
She was jailed at Sheffield Crown Court on Wednesday after being found guilty of fraud.
Turner provided daily care to residents with various vulnerabilities at a complex in Sheffield and became more involved in the running of the business in 2006 when the owner was ill.
Over the next decade, police said she took about £923, 000 from 10 victims by linking her bank account with theirs and using their bank cards to regularly withdraw money after they had been paid benefits.
Turner used the money to buy a static caravan worth almost £60,000, two properties in Dubai, three properties in England, numerous holidays to the Middle East and high-value cars.
She was sacked and the police alerted after the business owner returned to work in 2016 and discovered that some residents' bank accounts had been linked to Turner's.
Turner, of Ecclesfield Court, Sheffield, was charged with two counts of fraud and was found guilty by a jury on Monday after a trial.
She was jailed for seven years on Wednesday.
Detective Constable James Hughes, from South Yorkshire Police, said: "Over 10 years, Turner selfishly and shamelessly took advantage of the vulnerable residents, taking possession and control of their bank cards, making regular - and often daily - bank withdrawals to fund the lavish lifestyle she was leading.
"She also set up standing orders from the victims' accounts to subsidise that lifestyle, which saw her buying a static caravan worth almost £60,000, two properties in Dubai, three properties in England and numerous holidays to the Middle East."
He continued: "During a three-year investigation, extensive banking data was analysed and the full extent of her fraudulent activity became known - it was believed that she took possession of a total of almost £923,000 from the ten vulnerable residents and benefited herself from £640,000.
"All of the residents she took advantage of are vulnerable due to their age, mental health, or due to substance abuse issues and many struggle to operate daily functions - they relied on her to get through life every single day and she callously took advantage of that."
Mr Hughes added: "The decade of control she exercised over the victims is absolutely abhorrent and I hope that they feel some comfort in knowing she has been jailed.
"To abuse her position as a carer with people who trusted her implicitly is absolutely disgusting and I'm pleased that the jury returned guilty verdicts and she will now serve a basic lifestyle in prison."