The former strongmen battled it out in the Dubai Duty Free Tennis Stadium, with The Mountain coming out on top by unanimous decision after six rounds.
Hall was the fan favourite in the stadium, and he rocked his opponent early as the crowd cheered him on, before knocking him to the canvas.
But Björnsson was able to bust open Hall's face in the first round, and in the third he knocked him down, in what for a moment looked like it could be a KO.
He went on to knock down Hall again in the sixth round, and the judges declared him winner, 57-54.
Friends turned foes Hall and Björnsson (otherwise known as 'The Beast' and 'Thor' respectively) are both World's Strongest Man winners, but they traded the barbells for boxing gloves for a fight that was billed as 'the heaviest boxing match in history'.
Speaking to LADbible ahead of the fight, 34-year-old Hall described his motivation as '100 percent hatred' and said that he was driven by a desire to 'get in the ring and break this f***er's face'.
That hatred stems from claims made by Björnsson in the aftermath of Hall's 2017 World’s Strongest Man win.
The pair were locked at the top of the standings before a controversial ruling in the 'Viking Press' event saw Thor docked a rep, which ultimately led to him losing the overall competition.
Subsequent unpleasant exchanges between the two behemoths appeared to show that the friendship they once shared had completely vanished, replaced with mutual contempt.
Hall was very confident he'd win the fight, and was adamant that it wasn't about the cash for him.
"The money is not the incentive for me," he told LADbible earlier this week.
"I'm already rich, I don't give a f**k about the money. This is about me and Thor now – this is personal."
Meanwhile, Thor predicted that Hall's anger would get the better of him, and his boxing skills would win the day.
He told LADbible in the run up to the bout: "I don't like the guy but I’m here to box and show the people my boxing skills, staying calm and staying relaxed.
"He is going to come in angry like a bull and is probably gonna gas out in the first round or second round because he's so angry and p***ed off. The man cannot control his emotions. He’s too focused on the past.
"He's too angry, he's like a 16-year-old boy, if you cannot control your emotions you cannot fight. There's no way that man can fight six rounds against me.
"My plan is to box, my plan is to show my skills and technique and show the people my ability in the boxing ring.
"If he is not ready, I'm going to knock him out soon. He's going to come in silly, throwing wild hooks – I have a longer reach.
"I'm going to catch him and he's gonna fall down, then we're going to hear some excuses."
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