UK light heavyweight Buatsi secured a victory yet unimpressive debut to his career under new promoters with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output seemingly secured him a majority decision in a tight ten-round fight at the Manchester venue.
But the challenger had his moments, landing some telling individual punches in a fight where the styles didn't complement each other, with excessive holding disrupting the action.
The scoring judges scored it 96-94 to Buatsi, with the third a 95-95 draw.
"It wasn't my greatest performance but what defines champions? They prevail," the victor commented in the arena as he was greeted with boos from the audience.
The Londoner returned to winning ways after his initial pro loss - an memorable fight with his previous opponent in February - to claim a twentieth professional win.
Various analysts felt the challenger, thirty-one, deserved the win but the contender endured the second defeat of his 28-match career.
Buatsi Claims Victory in Dull Encounter
His career development has plateaued in recent times through promotional disputes and extended periods of inactivity.
Once tipped as the rising talent of British boxing, he now finds himself trying to fulfil that early promise - perhaps in what feels like a last chance - under recent support.
He began cautiously, with both competitors willing to be aggressive in a cagey initial rounds.
The challenger, whose single earlier setback came at the lower weight class against his former opponent in two years ago after breaking his hand mid-fight, was making just his second appearance at light-heavyweight.
By the middle rounds, the underdog had kept it close, creating difficulties for Buatsi, who worked behind a solid defense to barely take the more effective periods.
The spectators' acceptance decreased amid frequent holding, with Parker falling to the floor various instances during close exchanges.
Parker ended stronger, but multiple periods were difficult to score. Although, former world champion the boxing analyst - commentating on Dazn - had it particularly wide for the challenger, giving Buatsi just one round.
The victor progresses, but with the likes of hard hitter David Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the journey to titles - based on this performance - still appears challenging.
Ricky Hatton Tribute Motivates Manchester Derby Fight
In the co-main event, Arthur overcame Rea by close verdict in a terrific local rivalry contest to win the continental belt.
The stadium grew hushed for a profoundly moving homage before the fight as 10 bells tolled in memory of Manchester's own Ricky Hatton, who succumbed aged 46 in September.
It was the premier televised fight night in the location since the passing of Hatton. As the last bell disappeared, the quiet gave way to a roar of "there's only one Ricky Hatton".
The fighting within the ring equaled the feeling. The eventual winner was floored by a left hook flush on the face in the early round, rising shakily to his position on the count of eight.
But the Manchester United-red equipment of the fighter soon advanced again. On the opposite side, Rea - in competitive blue - was injured soon, noticeable damage developing under his orbital area as the pair traded hard punches.
The challenger, 27, connected with strong blows but Arthur, thirty-four, matched the intensity with stinging uppercuts as the action seldom decreased over 12 rounds.
Arthur edged the result with scoring tallies of 114-114, 115-113 and clearer margin, but the two athletes were relentless and full of heart, everything their inspiration Hatton represented.
