UK light heavyweight Buatsi earned a win yet underwhelming debut to his career under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's work rate seemingly secured him a judges' verdict in a close 10-round fight at the boxing arena.
But Parker had his moments, connecting with powerful clean blows in a fight where the approaches failed to mesh, with frequent clinching spoiling the fight.
The officials scored it 96-94 in favor to Buatsi, with the final judge a 95-95 draw.
"It wasn't my greatest performance but what do champions do? They prevail," the victor said in the arena as he was greeted with negative reactions from the crowd.
The British fighter got back to winning after his maiden career setback - an memorable fight with Callum Smith in February - to secure a 20th career victory.
Some ringside observers thought the challenger, thirty-one, should have been awarded the victory but the contender endured the second setback of his 28-match professional journey.
The Champion Secures Triumph in Dull Affair
His career development has plateaued in recent years through promotional disputes and considerable time of inactivity.
Earlier forecast as the next star of British boxing, he now finds himself trying to fulfil that early promise - maybe in what feels like a last chance - under fresh management.
He started carefully, with the two boxers willing to take risks in a tentative initial rounds.
The challenger, whose single earlier setback came at super-middleweight against John Ryder in two years ago after breaking his hand mid-fight, was participating in his second bout at light-heavyweight.
By the middle rounds, Parker had kept it close, creating difficulties for the favorite, who utilized a tight guard to barely take the more effective rounds.
The crowd's patience decreased amid regular grabbing, with Parker going down multiple occasions during grappling.
The underdog closed well, but several stanzas were challenging to assess. Although, previous titleholder Carl Frampton - providing analysis for Dazn - had it significantly in favor for Parker, giving Buatsi just a single round.
The victor progresses, but with the likes of heavy hitter Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the journey to titles - on this evidence - still seems difficult.
Hatton Homage Inspires All-Manchester Fight
In the co-main event, Arthur overcame Rea by divided decision in a outstanding Manchester vs Manchester battle to secure the European light heavyweight belt.
The arena grew hushed for a deeply poignant homage before the fight as 10 bells sounded in memory of local hero Hatton, who died aged 46 in September.
It was the initial significant broadcast match card in the urban center since Hatton's death. As the last bell ended, the quiet transitioned to a roar of "there's just one Hatton".
The competition within the ring reflected the emotion. Arthur was sent to the canvas by a significant blow directly to the chin in the early round, getting up unsteadily to his footing on the eight count.
But the traditional red equipment of the fighter soon came forward again. On the opposite side, the opponent - in opposing blue - was damaged quickly, noticeable damage developing under his orbital area as the duo exchanged punishing blows.
The challenger, 27, landed power punches but the champion, thirty-four, responded in kind with powerful upward punches as the intensity rarely dropped over 12 rounds.
Arthur narrowly won the result with official scores of 114-114, close margin and 115-112, but each competitor were determined and full of heart, exactly what their inspiration the legend embodied.
