British light heavyweight Buatsi made a winning yet underwhelming beginning to his career under fresh promotional backing with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level appeared to earn him a split decision in a tight ten-round fight at the Co-op Live Arena.
But the challenger found success, landing some telling single shots in a fight where the styles didn't complement each other, with constant grabbing spoiling the fight.
The scoring judges had it 96-94 for to Buatsi, with the third a even score.
"It wasn't my finest display but what defines champions? They succeed," Buatsi said in the ring as he was greeted with boos from the spectators.
The Londoner returned to winning ways after his maiden career setback - an epic battle with Callum Smith in last winter - to claim a 20th career victory.
Various analysts believed Parker, 31, deserved the decision but the British boxer endured the second loss of his 28-bout professional journey.
The Champion Secures Win in Dull Encounter
Buatsi's progress has stalled in recent years through promotional disputes and long spells of inactivity.
Once tipped as the rising talent of UK boxing, he now finds himself trying to fulfil that early promise - maybe in what seems like a final roll of the dice - under recent support.
He started carefully, with the two boxers ready to overcommit in a tentative early stages.
The challenger, whose only previous defeat came at super middleweight 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, Parker had stayed in contention, creating difficulties for the favorite, who operated with a protective stance to edge the more effective rounds.
The spectators' acceptance diminished amid constant clinching, with Parker going down multiple occasions during clinches.
The underdog closed well, but multiple periods were challenging to assess. Although, previous titleholder the boxing analyst - providing analysis for Dazn - had it significantly in favor for Parker, giving Buatsi just a single round.
The victor progresses, but with the caliber of power puncher Benavidez, and Eastern European fighter Bivol ruling the division, the road to world glory - based on this performance - still appears challenging.
Hatton Memorial Fuels All-Manchester Battle
In the supporting bout, Arthur overcame Bradley Rea by close verdict in a outstanding all-Manchester contest to secure the European light heavyweight championship.
The stadium fell silent for a profoundly moving homage prior to the bout as a bell ceremony sounded in memory of local hero Hatton, who died at age 46 in recently.
It was the first major televised match card in the urban center since Hatton's passing. As the concluding sound ended, the quiet gave way to a shout of "there's just one Hatton".
The action during the bout matched the emotion. Arthur was sent to the canvas by a powerful punch squarely on the jaw in the second round, getting up unsteadily to his feet on the eight count.
But the red-colored shorts of Arthur soon came forward again. On the opposite side, the opponent - in competitive blue - was marked up soon, noticeable damage forming under his orbital area as the pair exchanged punishing blows.
Rea, twenty-seven, connected with strong blows but the champion, thirty-four, matched the intensity with effective uppercuts as the intensity seldom decreased over 12 rounds.
Arthur barely secured the verdict with official scores of draw, narrow lead and wider gap, but each competitor were relentless and full of heart, exactly what their hero Hatton represented.
