UK light-heavyweight Buatsi made a winning yet underwhelming beginning to life under fresh promotional backing with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's punch output likely gained him a majority decision in a competitive 10-round contest at the Manchester venue.
But the challenger landed significant shots, landing some telling clean blows in a fight where the techniques never quite clicked, with constant grabbing disrupting the contest.
Two judges judged it 96-94 to Buatsi, with the third a 95-95.
"It wasn't my finest performance but what do champions do? They succeed," the victor stated in the ringside as he was met by negative reactions from the crowd.
The British fighter returned to winning ways after his first professional defeat - an thrilling contest with his previous opponent in last winter - to earn a twentieth professional win.
Some ringside observers felt Parker, 31, merited the decision but the contender experienced the second setback of his 28-fight professional journey.
Buatsi Earns Triumph in Dull Encounter
The fighter's advancement has stalled in recent years through promotional disputes and long spells of inactivity.
Previously predicted as the rising talent of the British fight scene, he now stands trying to realize his potential - maybe in what feels like a ultimate opportunity - under recent support.
He began cautiously, with the two boxers ready to take risks in a calculated opening few rounds.
Parker, whose sole prior loss came at super middleweight against John Ryder in 2022 after suffering a hand injury mid-fight, was participating in his second fight at light-heavyweight.
By the fight's midpoint, Parker had kept it close, making life awkward for the favorite, who operated with a tight guard to barely take the more effective rounds.
The crowd's patience diminished during frequent holding, with Parker slipping to the canvas multiple occasions during clinches.
Parker ended stronger, but several stanzas were hard to judge. However, ex-champion Carl Frampton - providing analysis for Dazn - had it significantly in favor for the challenger, giving Buatsi just only one stanza.
Buatsi moves on, but with the presence of heavy hitter David Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the path to championship success - judging by this showing - still seems difficult.
Hatton Tribute Fuels Manchester Derby Fight
In the secondary fight, Lyndon Arthur beat Rea by close verdict in a terrific Manchester vs Manchester fight to capture the continental title.
The venue grew hushed for a profoundly moving memorial before the fight as ten bells sounded in remembrance of Manchester's own Hatton, who died aged 46 in last month.
It was the first major televised match card in the city since Hatton's death. As the concluding sound disappeared, the silence gave way to a shout of "there's just one Ricky Hatton".
The competition within the ring equaled the feeling. Arthur was sent to the canvas by a significant blow flush on the face in the initial stage, getting up unsteadily to his feet on the count of eight.
But the traditional red shorts of the fighter soon advanced again. Across the ring, the opponent - in opposing blue - was injured soon, noticeable damage developing under his face as the duo landed punishing blows.
The challenger, twenty-seven, connected with strong blows but Arthur, 34, fought fire with fire with stinging uppercuts as the intensity seldom decreased over 12 rounds.
Arthur edged the decision with scoring tallies of draw, 115-113 and clearer margin, but each competitor were persistent and full of heart, everything their idol Hatton stood for.
