UK light-heavyweight Buatsi made a winning yet underwhelming beginning to his career under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic medal winner's punch output seemingly secured him a split decision in a competitive 10-round contest at the Manchester venue.
But the challenger had his moments, landing some telling individual punches in a match where the techniques didn't complement each other, with excessive holding spoiling the fight.
The scoring judges had it 96-94 in favor to Buatsi, with the third a 95-95.
"It wasn't my greatest performance but how do champions respond? They succeed," the victor said in the ringside as he was met by disapproval from the spectators.
The Londoner got back to winning after his initial pro loss - an epic battle with his previous opponent in last winter - to claim a twentieth professional win.
Some ringside observers believed the challenger, 31, should have been awarded the victory but the contender endured the second loss of his 28-bout career.
The Champion Secures Triumph in Uneventful Affair
Buatsi's progress has plateaued in recent years through contract problems and extended periods of inactivity.
Once tipped as the rising talent of the British fight scene, he now is positioned trying to fulfil that early promise - possibly in what feels like a last chance - under recent support.
He began cautiously, with neither fighter willing to overcommit in a calculated early stages.
The challenger, whose single earlier setback came at super-middleweight against John Ryder in 2022 after damaging his hand mid-fight, was competing in only his second fight at the higher weight class.
By the fight's midpoint, the underdog had made it competitive, creating difficulties for the favorite, who operated with a tight guard to narrowly win the more effective stanzas.
The spectators' acceptance diminished during regular grabbing, with the challenger slipping to the canvas several times during grappling.
Parker finished the stronger, but multiple periods were challenging to assess. However, former world champion Carl Frampton - working with the broadcast network - had it significantly in favor for Parker, scoring for Buatsi just only one stanza.
The victor advances, but with the likes of hard hitter David Benavidez, and Eastern European fighter Bivol dominating the weight class, the road to world glory - based on this performance - still looks steep.
Hatton Memorial Fuels All-Manchester Battle
In the secondary fight, Arthur defeated Bradley Rea by divided decision in a excellent local rivalry battle to win the European light-heavyweight championship.
The stadium grew hushed for a extremely emotional tribute prior to the bout as 10 bells sounded in honor of Manchester's own Ricky Hatton, who succumbed aged 46 in last month.
It was the first major televised fight night in the urban center since Hatton's death. As the final chime faded, the stillness transitioned to a roar of "there's just one Ricky Hatton".
The competition during the bout equaled the emotion. The eventual winner was knocked down by a left hook directly to the jaw in the early round, getting up unsteadily to his feet on the eight count.
But the Manchester United-red attire of the fighter soon advanced again. On the opposite side, Rea - in competitive blue - was injured early, heavy swelling forming under his orbital area as the pair traded hard punches.
The challenger, 27, delivered effective strikes but the champion, 34, fought fire with fire with effective uppercuts as the pace rarely dropped over 12 rounds.
Arthur barely secured the verdict with scoring tallies of even score, close margin and wider gap, but both fighters were relentless and full of heart, all the qualities their idol Hatton stood for.
