UK light heavyweight Buatsi secured a victory yet disappointing start to his career under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic medal winner's punch output likely gained him a split decision in a tight 10-round contest at the boxing arena.
But the challenger had his moments, connecting with powerful clean blows in a contest where the techniques never quite clicked, with constant grabbing disrupting the fight.
Two judges scored it 96-94 to the winner, with the final judge a 95-95.
"It wasn't my greatest showing but what defines champions? They succeed," the victor stated in the ringside as he was greeted with negative reactions from the spectators.
The Londoner bounced back after his maiden career setback - an memorable fight with Callum Smith in February - to claim a 20th career victory.
Several boxing experts thought Parker, 31, merited the victory but the contender endured the second loss of his 28-bout career.
The Champion Earns Victory in Dull Encounter
Buatsi's progress has plateaued in recent times through promotional disputes and considerable time of inactivity.
Once tipped as the future of the British fight scene, he now stands trying to realize his potential - perhaps in what seems like a ultimate opportunity - under recent support.
He opened tentatively, with neither fighter ready to overcommit in a tentative initial rounds.
Parker, whose sole prior loss came at super-middleweight against his former opponent in 2022 after damaging his hand in the contest, was participating in his second appearance at light heavyweight.
By the fight's midpoint, the underdog had made it competitive, making life awkward for the favorite, who operated with a tight guard to barely take the more effective rounds.
The spectators' acceptance wore thin because of regular grabbing, with the challenger going down several times during grappling.
Parker ended stronger, but several stanzas were hard to judge. Although, previous titleholder Carl Frampton - providing analysis for the broadcast network - had it strongly leaning for the challenger, giving Buatsi just only one stanza.
Buatsi advances, but with the caliber of hard hitter David Benavidez, and Russian star Bivol dominating the weight class, the road to world glory - based on this performance - still looks steep.
Ricky Hatton Memorial Motivates All-Manchester Contest
In the co-main event, Lyndon Arthur beat Bradley Rea by split-decision in a excellent all-Manchester battle to secure the European light-heavyweight title.
The venue became quiet for a deeply poignant homage prior to the bout as ten bells rang in remembrance of the city's native Hatton, who succumbed 46 years old in September.
It was the premier televised match card in the urban center since the passing of Hatton. As the final chime disappeared, the silence became a chant of "there's just one Hatton".
The competition within the ring reflected the feeling. Arthur was knocked down by a significant blow directly to the face in the initial stage, rising shakily to his feet on the count of eight.
But the red-colored attire of Arthur soon pressed ahead again. On the opposite side, the opponent - in opposing blue - was marked up quickly, significant bruising appearing under his face as the pair traded punishing blows.
The challenger, twenty-seven, connected with strong blows but Arthur, 34, matched the intensity with effective uppercuts as the action hardly diminished over twelve rounds.
Arthur narrowly won the result with official scores of even score, close margin and clearer margin, but each competitor were relentless and courageous, everything their hero the legend embodied.
