Former off-shore worker William Kelly, 42, shouted “die, die” as his mother Cathy Kelly was engulfed in flames.
Following the blaze Kelly’s only concern was the safety of his West Highland terrier Poppy.
Minutes earlier Kelly had violently punched and kicked his mother leaving her lying face down on the living room floor.
After deliberating for 90 minutes the jury at the High Court in Glasgow unanimously convicted Kelly of murdering his mother.
He now faces a life sentence with a minimum of 23 years behind bars before he can be considered for release.
Jailing Kelly for life judge Lady Stacey said: “I understand you maintain your denial of the crime and have shown no remorse.
“I also note from having heard the evidence that you said a few weeks after your mother’s death you did what you had to and she deserved what she got.”
She said: “The jury found you guilty of murdering your mother, you assaulted her by pushing her and putting her to the floor before you poured petrol on her and set her alight – that is a horrific crime.”
The judge added: “She looked after you and brought you up, even near the end of her life she was still prepared to cherish you as her son and excused your bad behaviour to other people.”
She said that Kelly “made her frightened” of him and “in the end he killed her”.
Earlier, jurors heard that Kelly broke off from the brutal assault to take a phone call which he answered in a silly voice claiming to be an Indian restaurant.
After finishing the call Kelly went back and further assaulted his defenceless mother – who always referred to him as ‘ma boy.’
Throughout his trial Kelly denied murdering his mother at the home they shared at Kilmaurs Road, Kilmarnock, on February 11.
He said he had never hit his mother and claimed she had been set on fire by accident.
He told the court he was cleaning a car part in the garage and spilt petrol on his trousers and trainers.
Kelly claimed that as he bent over his mother as she lay on the living room floor he lit a cigarette and there was a blue flash.
But the jury heard that there was no trail of petrol from the garage into the living room. They were also told by a fire expert that if the fire had happened as Kelly claimed he would have more badly injured.
The court heard that Kelly was raging because his mother had embarrassed him at a 21st birthday party by drinking too much. He ordered his mother and his then partner Eleanor Banks to leave and called a taxi.
When they returned home around 11pm he dragged his mother by the arms into the house after she fell as she got out the taxi.
Kelly then punched and kicked the helpless OAP on the head and body in the living room of their home.
Mrs Banks, 44, told prosecutor Ashley Edwards QC: “William was emptying a petrol can onto his mum – all over her – and I couldn’t stop him.
“I was standing screaming ‘You’re going to kill your mum’ and he was saying ‘die’ The liquid smelled like petrol.
“He went down and he set fire at the bottom of her legs.
“She just went up like an inferno. I’ve never seen anything like it. In the blink of an eye she was on fire.”
A pathologist said that Cathy suffered bruising, broken ribs and second degree burns to 45 per cent to her body. She also had a cut to her tongue and bruised lips.
Forensic scientists revealed that the top Cathy was wearing that night was saturated in petrol.
Jurors heard that Cathy was recovering from a brain haemorrhage which she suffered in December 2016 and it was alleged that this was caused by beatings inflicted by violent Kelly.
Heartless Kelly even boasted in a text sent in early December 2016 of wanting to give his mother “two black eyes for Christmas.”
When Kelly was in the Royal Infirmary in Glasgow being treated for burns he confessed to a nurse who was treating him saying: “I did what I had to do. I was provoked. She got what she deserved.”
Kelly’s sister Mrs Catherine Cree, 53, a deputy charge nurse at Crosshouse Hospital, Kilmarnock, told the court in March or April 2016 her brother became angry and annoyed with their mother after she allowed someone into the house to look at pigeons kept in the back garden.
She said: “He bawled and shouted at her a lot. My mum was reduced to tears. He couldn’t talk things through with her. He just shouted at her. That was William’s way most of the time if he was angry.”
Mrs Cree was estranged from her mother in the last nine months of her life after a row over Poppy the dog and was disinherited by her. Previously they had had a close and loving relationship.
Gordon Jackson QC defending, said: “Mr Kelly’s position is absolutely as it was, there’s no indication that will change.”