Teresa Wright, 44, spent her son Michael’s money on a £100,000 caravan, weekends away, and gave her other children cash handouts.
Mr Wright, now 27, had received the payout after a car crash in June 2007, which left him with a life changing head injury and reduced mental capacity.
The compensation was paid into a bank account administered by the Court of Protection, and his mother was appointed a Deputy to manage his financial affairs.
Each time his mother would have to fill in paperwork for the court, which would then hand the money over.
Neil King, prosecuting, said: ‘This defendant chose to fraudulently take a significant sum from her vulnerable son, when she was supposed to be acting in his best interests.’
In the years after the accident, Mr Wright spent nearly £700,000 on a house, £150,000 on an Aston Martin and shelled out more than £20,000 on a Mitsubishi Warrior motorbike.
His condition eventually improved and he planned to invest in some buy-to-let properties using £400,000 that was still in the account, so he would have an income, the court heard.
Mr King said: ‘He wanted his mother to withdraw this balance so that he could invest.
‘He describes a repeated period of being ‘fobbed off’ by his mother.
‘Eventually, in 2013, his capacity having improved, he applied to the court and he took control of the compensation bank account. What he discovered shocked him.’
In September 2012, his mother had allegedly requested £400,000 be withdrawn from the Court of Protection bank account, claiming it was for investment.
A week later, the cash was paid into the bank account she ran for her son, which was moved between accounts and ended in her account by the end of October 2012.
Police found Mrs Wright had withdrawn large sums in cash, money had been handed over to her other children, and more than £100,000 was spent on a caravan – which her son knew nothing of.
Giving evidence, Mr Wright said he spoke to his mother about his plans to invest in property.
He said: ‘I was told that the money wasn’t there, when it was funding her weekends away.
‘A good six, seven years she had not been working.
‘I was 18 in the car crash. Growing up to be an adult, I wanted to be in control of my own finances and affairs.
‘She told me there is no way the court would allow me to take control of my finances.’
Mr Wright added: ‘Growing up, I had everything you could imagine. Mum and Dad treated us well. But it doesn’t give her the right to disappear with my funds.’
Mrs Wright, of Wellingborough, Northamptonshire, claimed that all the money was spent at her son’s request, but a jury at Luton Crown Court convicted her of one count of fraud by abuse of position between September 2012 and May 2016.
Speaking after the case Mr Wright said: ‘Its been touch and go but got the result we were hoping for at the end.
‘She hasn’t been sentenced yet but on the whole I can now finally close the door on it all and have it all dealt with.’