British light heavyweight Buatsi made a winning yet disappointing beginning to his career under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's work rate likely gained him a majority decision in a competitive ten-round contest at the Co-op Live Arena.
But the challenger had his moments, delivering effective single shots in a contest where the styles failed to mesh, with excessive holding spoiling the fight.
The scoring judges had it 96-94 for to the winner, with the third a 95-95 draw.
"It wasn't my greatest performance but what do champions do? They win," Buatsi said in the ring as he was faced disapproval from the audience.
The British fighter bounced back after his first professional defeat - an epic battle with Callum Smith in February - to secure a twentieth professional win.
Some ringside observers felt Parker, 31, deserved the victory but the contender endured the second loss of his 28-match professional journey.
Buatsi Earns Victory in Dull Affair
His career development has stalled in recent times through contract problems and considerable time of inactivity.
Previously predicted as the rising talent of British boxing, he now is positioned trying to fulfil that early promise - possibly in what feels like a ultimate opportunity - under new promotional backing.
He opened tentatively, with both competitors ready to overcommit in a calculated initial rounds.
Parker, whose single earlier setback came at the lower weight class against his former opponent 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, causing problems for the favorite, who worked behind a protective stance to narrowly win the more effective rounds.
The crowd's patience diminished because of constant clinching, with the challenger slipping to the canvas various instances during grappling.
Parker finished the stronger, but many rounds were difficult to score. Although, ex-champion Carl Frampton - working with Dazn - had it significantly in favor for the challenger, awarding Buatsi just a single round.
The victor advances, but with the caliber of hard hitter David Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the path to championship success - judging by this showing - still looks steep.
Ricky Hatton Memorial Motivates All-Manchester Battle
In the co-main event, Lyndon Arthur defeated Rea by close verdict in a outstanding Manchester vs Manchester fight to secure the European light heavyweight belt.
The stadium became quiet for a extremely emotional memorial prior to the bout as a bell ceremony tolled in honor of Manchester's own Hatton, who died 46 years old in last month.
It was the first major televised fight night in the location since the passing of Hatton. As the last bell faded, the silence became a shout of "only one Hatton".
The competition within the ring matched the emotion. The eventual winner was sent to the canvas by a left hook directly to the chin in the second round, getting up unsteadily to his feet on the eight count.
But the Manchester United-red shorts of the fighter soon pressed ahead again. On the opposite side, Rea - in competitive blue - was marked up early, significant bruising appearing under his face as the duo traded powerful shots.
The challenger, 27, delivered effective strikes but Arthur, 34, matched the intensity with powerful upward punches as the intensity rarely dropped over 12 rounds.
The victor narrowly won the decision with judges scorecards of even score, narrow lead and 115-112, but both fighters were relentless and brave, all the qualities their inspiration Hatton represented.
