UK light heavyweight Buatsi secured a victory yet underwhelming beginning to life under new promoters with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's work rate seemingly secured him a judges' verdict in a competitive 10-round bout at the Co-op Live Arena.
But the challenger found success, connecting with powerful clean blows in a match where the styles never quite clicked, with frequent clinching spoiling the contest.
The officials scored it 96-94 to the winner, with the remaining official a 95-95.
"It wasn't my best display but what defines champions? They succeed," Buatsi commented in the ring as he was faced disapproval from the crowd.
The British fighter got back to winning after his initial pro loss - an epic battle with Callum Smith in last winter - to secure a twentieth professional win.
Various analysts thought Parker, thirty-one, deserved the win but the Derbyshire fighter experienced the second loss of his 28-bout career.
Buatsi Claims Win in Dull Affair
Buatsi's progress has plateaued in recent times through contract problems and long spells of lack of fights.
Once tipped as the future of the British fight scene, he now stands trying to realize his potential - perhaps in what appears to be a final roll of the dice - under new promotional backing.
He started carefully, with the two boxers willing to be aggressive in a tentative initial rounds.
Parker, whose single earlier setback came at super middleweight against John Ryder in two years ago after suffering a hand injury mid-fight, was making just his second appearance at light-heavyweight.
By the fight's midpoint, Parker had stayed in contention, making life awkward for Buatsi, who worked behind a tight guard to narrowly win the better periods.
The spectators' acceptance diminished during regular grabbing, with the challenger going down multiple occasions during grappling.
The underdog finished the stronger, but many rounds were hard to judge. However, former world champion the boxing analyst - working with the broadcast network - had it strongly leaning for the challenger, giving Buatsi just one round.
Buatsi moves on, but with the likes of hard hitter David Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the road to world glory - based on this performance - still looks steep.
Hatton Homage Inspires All-Manchester Contest
In the co-main event, Lyndon Arthur overcame Bradley Rea by close verdict in a terrific all-Manchester contest to win the continental championship.
The arena grew hushed for a deeply poignant tribute before the fight as a bell ceremony tolled in remembrance of Manchester's own Ricky Hatton, who succumbed aged 46 in recently.
It was the initial significant broadcast boxing event in the urban center since Hatton's death. As the concluding sound ended, the quiet gave way to a chant of "only one Hatton".
The action inside the ropes equaled the sentiment. The eventual winner was knocked down by a left hook flush on the face in the second round, standing uncertainly to his feet on the count of eight.
But the Manchester United-red shorts of the fighter soon advanced again. Across the ring, Rea - in rival City blue - was damaged quickly, noticeable damage forming under his orbital area as the pair landed powerful shots.
Rea, twenty-seven, connected with strong blows but Arthur, thirty-four, responded in kind with stinging uppercuts as the action hardly diminished over 12 rounds.
Arthur edged the decision with judges scorecards of 114-114, 115-113 and wider gap, but both fighters were determined and brave, exactly what their inspiration the legend represented.
