UK light-heavyweight Buatsi earned a win yet disappointing beginning to life under fresh promotional backing with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output appeared to earn him a judges' verdict in a close 10-round fight at the Co-op Live Arena.
But Parker found success, connecting with powerful single shots in a fight where the styles didn't complement each other, with frequent clinching marring the contest.
Two judges scored it 96-94 to Buatsi, with the third a 95-95 draw.
"It wasn't my best showing but how do champions respond? They succeed," the victor stated in the ringside as he was faced boos from the crowd.
The Londoner returned to winning ways after his maiden career setback - an thrilling contest with his previous opponent in February - to earn a twentieth professional win.
Some ringside observers believed Parker, thirty-one, merited the victory but the contender experienced the second loss of his 28-bout professional journey.
Buatsi Claims Win in Slow Match
The fighter's advancement has stalled in recent years through promotional disputes and long spells of inactivity.
Earlier forecast as the next star of British boxing, he now finds himself trying to realize his potential - maybe in what seems like a final roll of the dice - under recent support.
He started carefully, with neither fighter prepared to take risks in a cagey initial rounds.
The challenger, whose only previous defeat came at the lower weight class against his former opponent in two years ago after suffering a hand injury in the contest, was making just his second bout at the higher weight class.
By the halfway stage, Parker had kept it close, making life awkward for the favorite, who worked behind a tight guard to edge the better stanzas.
The audience's tolerance wore thin amid constant clinching, with Parker going down multiple occasions during close exchanges.
The underdog ended stronger, but several stanzas were hard to judge. Nevertheless, former world champion the boxing analyst - working with the broadcast network - had it strongly leaning for the challenger, scoring for Buatsi just a single round.
The victor moves on, but with the caliber of hard hitter David Benavidez, and Eastern European fighter Bivol dominating the weight class, the journey to titles - based on this performance - still looks steep.
Hatton Tribute Motivates Local Rivalry Contest
In the supporting bout, Lyndon Arthur beat Rea by close verdict in a outstanding local rivalry contest to win the continental championship.
The venue grew hushed for a profoundly moving tribute ahead of the contest as ten bells tolled in honor of local hero Hatton, who died at age 46 in September.
It was the initial significant broadcast boxing event in the location since the passing of Hatton. As the final chime faded, the quiet became a shout of "there's only one Hatton".
The action within the ring reflected the emotion. The eventual winner was sent to the canvas by a powerful punch flush on the jaw in the early round, getting up unsteadily to his feet on the eight count.
But the red-colored attire of Arthur soon came forward again. From the other corner, the opponent - in rival City blue - was marked up soon, heavy swelling appearing under his face as the pair landed hard punches.
The challenger, 27, delivered effective strikes but the champion, 34, matched the intensity with powerful upward punches as the pace rarely dropped over 12 rounds.
The victor barely secured the verdict with judges scorecards of even score, narrow lead and clearer margin, but the two athletes were relentless and full of heart, all the qualities their hero Hatton embodied.
