UK light-heavyweight Buatsi secured a victory yet underwhelming start to his career under recent management with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate appeared to earn him a split decision in a tight ten-round bout at the boxing arena.
But Parker landed significant shots, connecting with powerful single shots in a fight where the approaches never quite clicked, with frequent clinching spoiling the action.
The scoring judges scored it 96-94 to Buatsi, with the third a 95-95.
"It wasn't my finest performance but what do champions do? They win," Buatsi commented in the arena as he was met by boos from the spectators.
The British fighter got back to winning after his maiden career setback - an memorable fight with his previous opponent in last winter - to secure a 20th career victory.
Several boxing experts thought the challenger, thirty-one, should have been awarded the decision but the contender suffered the second defeat of his 28-fight career.
Buatsi Earns Triumph in Uneventful Affair
The fighter's advancement has stalled in the past few years through promotional disputes and long spells of inactivity.
Earlier forecast as the future of UK boxing, he now finds himself trying to achieve expectations - possibly in what feels like a final roll of the dice - under recent support.
He opened tentatively, with the two boxers prepared to take risks in a cagey early stages.
Parker, whose sole prior loss came at super middleweight against John Ryder in 2022 after suffering a hand injury in the contest, was competing in only his second appearance at light-heavyweight.
By the middle rounds, the underdog had kept it close, making life awkward for Buatsi, who operated with a solid defense to edge the better periods.
The spectators' acceptance decreased because of constant clinching, with Parker slipping to the canvas various instances during grappling.
Parker closed well, but many rounds were difficult to score. However, previous titleholder Carl Frampton - working with Dazn - had it strongly leaning for the challenger, giving Buatsi just one round.
Buatsi advances, but with the caliber of power puncher Benavidez, and Eastern European fighter Bivol ruling the division, the road to world glory - judging by this showing - still looks steep.
Hatton Homage Inspires All-Manchester Battle
In the supporting bout, Lyndon Arthur beat Bradley Rea by close verdict in a terrific all-Manchester battle to capture the European light-heavyweight championship.
The venue grew hushed for a extremely emotional homage prior to the bout as 10 bells sounded in remembrance of the city's native Ricky Hatton, who died 46 years old in recently.
It was the initial significant broadcast fight night in the location since Hatton's passing. As the concluding sound faded, the quiet transitioned to a shout of "there's just one Ricky Hatton".
The competition inside the ropes equaled the sentiment. Arthur was knocked down by a powerful punch squarely on the chin in the initial stage, getting up unsteadily to his position on the eight count.
But the traditional red equipment of the fighter soon advanced again. From the other corner, the opponent - in opposing blue - was marked up early, noticeable damage forming under his orbital area as the fighters landed powerful shots.
The challenger, 27, landed power punches but Arthur, 34, matched the intensity with stinging uppercuts as the intensity seldom decreased over twelve rounds.
The victor narrowly won the decision with scoring tallies of draw, 115-113 and 115-112, but both fighters were persistent and brave, exactly what their idol the legend represented.
