Samantha Rowley "frittered away" money that was supposed to be for her sibling's care on luxury holidays, Wembley tickets, beauty treatments and shopping sprees.
Leeds Crown Court heard Rowley enlisted the help of her friend Lynne Barrett to commit the offences during a four-year deception.
James Lake, prosecuting, said the offending related to Rowley's brother, Paul Rowley.
Mr Rowley was the victim of a hit-and-run accident in 1985 when he was 15 years old.
He suffered injuries which left him with severe learning disabilities and serious complex health conditions.
As a result of the accident he received over £1 million in compensation.
Mr Rowley died in 2021 after an investigation into his sister was underway.
The court heard Mr Rowley was deemed to lack capacity to make his own decisions around his health and his finances.
His finances were managed under a power of attorney which was granted to his sister in 2015.
Mr Rowley lived in an adapted five-bedroom house in Farnley with his sister and their mother, Elaine Rowley, until she died in December 2017.
He also had carers who would come to the home to look after him and were paid for by Leeds City Council
Lynne Barrett was recorded as one of the carers for both Mr Rowley and Elaine Rowley.
Samantha Rowley was responsible for creating a rota each week to facilitate the care needed for Elaine Rowley and Mr Rowley.
Each carer would submit weekly time sheets to Rowley showing the hours they worked.
Time sheets were then signed by the relevant carer and counter signed by Rowley.
Rowley and Barrett’s fraud was uncovered when a new social worker was assigned to work with Mr Rowley.
Concerns were raised by other carers to the social worker about fraudulent activity.
The social worker spoke to Rowley in April 2019 and they discussed the role of Barrett.
Rowley told her she was a friend who covered night shifts looking after her brother.
She denied any wrongdoing and claimed the other carers were lying.
Rowley met again with the social worker the following month.
She provided a letter explaining that she had claimed wages in the name of Barrett.
Rowley said she was doing night care for Mr Rowley and suggested that she was entitled to the money.
She also stated that Barrett would transfer the wages she received into her personal bank account.
Mr Lake said: "In summary, Lynne Barrett was obtaining fraudulent wages on the back of falsified timesheets in relation to the care of Mr Rowley for over four years."
Barrett fraudulently received wages between August 2014 to February 2019 to the total of £37,489.
Banking evidence revealed that Barrett usually transferred the wages into Rowley's account on the day they were paid to her
During the investigation, it came to light that Mr Rowley owned a property which had been sold.
The money obtained from the sale was £73,302 and had been paid into Mr Rowley’s bank account.
Rowley conducted the sale process and provided information to the Court of Protection that the reason for the sale was “to be able to adapt where he is living and have regular income to do as he chooses with carers and family”.
It was later revealed that no adaptations had been made to the property.
Mr Lake continued: "The money obtained from the sale went into Mr Rowley’s bank account.
"From the account there are debits which have been named to imply they are for improvements.
"On analysis of these debits, it is clear that the money was being transferred into a second account held Mr Rowley and used by Samantha Rowley for her day to day living which included holidays.
"There were also cash withdrawals from the account with the reference ‘wages’.
"This was plainly a fictitious reference used by Samantha Rowley to try and legitimise the cash withdrawals."
The investigation revealed around £98,000 of Mr Rowley's money was unaccounted for.
Mr Lake said analysis of the spending demonstrated that Rowley ‘frittered’ away Mr Rowley’s money over a three year period.
The spending included references to holidays, Wembley tickets, Christmas gifts, birthday money and beauty treatments.
There were purchases at high street stores such as Argos, Asda, Wickes, Next, Clarks, Primark, Sports Direct, Tesco, Schuh, River island, The Perfume Shop, Mothercare World and H Samuel.
There were also purchases at Brewers Fayre, Monsoon, Stratstone BMW, Costa Coffee, KFC, Fazenda, Littlewoods, AMF Bowling and Goldsmiths.
Rowley, 40, now of Hampden Road, Leyland, Lancashire, pleaded guilty to one count of fraud and one of fraud by abuse of position.
She has a previous conviction for fraud, committed in 2016.
Barrett, 54, of Poplar Way, Bramley, pleaded guilty to one count of fraud.
Sean Smith, mitigating for Rowley, said: "The defendant has known for some time that she is facing an immediate prison sentence."
Mr Smith Rowley has a six-year-old son.
Rowley was jailed for three years and four months.
Barrett was given a 15-month sentence, suspended for 24 months.
She was told she must complete 20 rehabilitation activity requirement days and do 150 hours of unpaid work.
Sentencing, Judge Robin Mairs told Rowley: "Your brother died in 2021.
"That money was there to safeguard his future and protect him.
"You were trusted to protect him and you betrayed that trust in the most greedy way imaginable by stripping away his money and spending it on yourself."
After the case, Coun Fiona Venner, Leeds City Council’s executive member for adult and children’s social care and health partnerships, said: “This is a truly shocking case where a system which supports some of the most vulnerable people in our society has been cynically exploited and abused for personal gain.
“Our adult social care staff dedicate themselves to supporting people with complex needs through a genuine desire to give vulnerable people the best lives and opportunities they possibly can.
“Fortunately, cases like this are extremely rare, but it is our hope that the sentence passed down by the court today will serve as a stern warning to anyone who would seek to manipulate the system and take vital time, money and resources away from those who need it most.”