Cameron Logan, 23, died in the blaze in Milngavie, East Dunbartonshire, and his girlfriend Rebecca Williams, 25, was seriously injured.
Last month, Blair Logan, 27, admitted murdering his brother and attempting to murder Ms Williams at the family home.
He said he doused his sibling in petrol and set him alight but did not mean to kill him.
At the High Court in Edinburgh, he was given a life sentence with a minimum jail term of 20 years before he can be considered for parole.
An earlier hearing was told that the brothers had a "hostile" relationship and had not spoken to each other since 2013.
In a letter read to the court, his parents said they found it "extremely difficult to reconcile the Blair that they know with the Blair that caused Cameron's death".
Both parents were in the court room in Edinburgh, along with Ms Williams and her family, as the sentence was passed by Lady Scott.
She said Cameron was a "happy and much loved young man" who had died a "horrible death" and that Logan "acted with wicked recklessness".
The judge accepted court reports that he had "abnormal personality traits" and features of autism spectrum disorder (ASD).
But she said there was no suggestion that Logan had a mental disorder and he was fully criminally responsible for his actions.
"Your motivation was malice," she said. "You had planned this attack for a considerable time."
Lady Scott said Logan's actions had also dramatically affected the life of Ms Williams, who sustained "truly terrible injuries", and his parents.
"At the time Miss Williams was employed in her dream job in radio broadcasting - you have robbed her of her voice and her career, of her future with Cameron and of her confidence and sense of self-worth. She remains disfigured, impaired and in pain," she added.
"Your act in setting this fire also endangered the lives of your own parents who were asleep upstairs. I cannot imagine the pain they will forever endure from what you did, losing in effect both their sons."
In a statement read by her father outside court, Ms Williams said Cameron Logan was a "caring, respectful and loving man" but their future together had been "stolen".
She added that no sentence would ever be enough for such a "barbaric and ruthless" murder.
"The horror of what happened in that room will haunt me forever," she said.
"Cameron died in the most cruel way, in front of my eyes. I can only imagine the pain and suffering he will have experienced in his final moments.
"I wish more than anything that I could have saved him."
An earlier hearing at the High Court in Glasgow heard that Blair Logan told police the brothers had not spoken since the death of their grandmother in 2013.
The attack was said to be in retaliation for a recent incident at the house when his brother had punched him.
On the night of the fire Cameron and Ms Williams slept on an inflatable mattress in the living room of the family home, after returning from a party at about 04:00.
Catherine Logan, the brothers' mother, went downstairs at 07:15 and saw a dark figure in the living room.
She saw him throw something that was on fire and then run out of the house - but she did not know who he was.
The court was told that when she turned back to the living room, she saw "orange and crackling" and the room turning black.
Cameron and Ms Williams were screaming.
Ms Williams managed to crawl into the kitchen but was unable to open the back door. She put her head in the fridge to protect herself from the fire before passing out.
Mr Logan senior tried to get into the living room but was beaten back by the intensity of the smoke and flames.
Ms Williams was rescued from the fire and treated in hospital for burns to her face, arms and hands and fire damage to her throat.
She has undergone "numerous" operations and has a tracheostomy in place which may be permanent.
Logan's parents were treated for smoke inhalation but were not badly injured - he admitted endangering their lives.
The family dog, Gomez, was also killed in the fire.
In mitigation, defence QC Shelagh McCall said Logan had shown genuine remorse and viewed the murder of his brother as "horrific" and said it could not be justified.
She told the court that the Logan had attempted suicide in prison and is under high observation.
A man who murdered his brother by setting fire to him has been ordered to spend at least 20 years in jail.