A convicted murderer, who became a hero when he confronted a terrorist near London Bridge in November 2019, will be pardoned, the UK's Daily Mirror newspaper reported.
Steven Gallant used an ornamental narwhal tusk to fight off attacker Usman Khan.
Under the royal prerogative of mercy, Gallant will have his sentence reduced and could be free by June 2021, if a parole board agrees he is not a danger to the public.
In 2005, Gallant, 42, was jailed for 17 years for beating a former firefighter, Barrie Jackson, to death outside a pub.
The Daily Mirror reported that the decision to free Gallant early was backed by at least one member of the victim's family.
“I have mixed emotions – but what happened at London Bridge goes to show the reality that people can change,” Jackson's son Jack, 21, said.
After his role in the London Bridge attack became public, Gallant said he would "never to turn to violence again".
"I can never bring that life back and it is right that I was handed a severe penalty for my actions. Once I'd accepted my punishment, I decided to seek help," he said.
In prison he learnt to read and write, started a business studies degree and took part in a rehabilitation project called Learning Together.
He was on day release and attended a Learning Together session in Fishmongers' Hall, near London Bridge, when Khan, who was also at the session, carried out the attack.
Among the victims was Jack Merritt, 25, Gallant’s former prison mentor, friend and conference co-ordinator.
"I could tell something was wrong and had to help," Gallant said after the attack.
"I saw injured people. Khan was standing in the foyer with two large knives in his hands. He was a clear danger to all, so I didn't hesitate."
Gallant used a wooden chair to keep Khan at bay and was handed a narwhal tusk as Khan ran towards him.
“Steve feels a debt of gratitude to all those who helped him to achieve a royal prerogative of mercy," Gallant's solicitor, Neil Hudgell, said.
“He is passionate about using his knowledge and experiences to help others steer away from crime.”