British light heavyweight Buatsi made a winning yet unimpressive debut to his career under fresh promotional backing with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's activity level seemingly secured him a majority decision in a competitive 10-round contest at the boxing arena.
But Parker landed significant shots, delivering effective individual punches in a fight where the styles never quite clicked, with frequent clinching spoiling the contest.
The scoring judges judged it 96-94 for to Buatsi, with the final judge a even score.
"It wasn't my finest showing but what do champions do? They win," the victor stated in the arena as he was faced boos from the crowd.
The Londoner got back to winning after his first professional defeat - an epic battle with Callum Smith in February - to secure a twentieth professional win.
Several boxing experts thought Parker, 31, should have been awarded the decision but the British boxer endured the second defeat of his 28-match career.
Buatsi Secures Victory in Uneventful Match
Buatsi's progress has stalled in recent times through management issues and considerable time of lack of fights.
Previously predicted as the rising talent of UK boxing, he now finds himself trying to achieve expectations - possibly in what seems like a ultimate opportunity - under fresh management.
He opened tentatively, with neither fighter prepared to take risks in a calculated early stages.
The challenger, whose single earlier setback came at super middleweight against his former opponent in two years ago after suffering a hand injury in the contest, was competing in only his second appearance at light heavyweight.
By the halfway stage, Parker had made it competitive, creating difficulties for the favorite, who operated with a tight guard to narrowly win the better rounds.
The crowd's patience wore thin amid frequent holding, with Parker slipping to the canvas several times during grappling.
The underdog ended stronger, but many rounds were difficult to score. Nevertheless, ex-champion the boxing analyst - providing analysis for Dazn - had it particularly wide for the challenger, scoring for Buatsi just only one stanza.
The victor moves on, but with the presence of heavy hitter David Benavidez, and Russian star Bivol ruling the division, the path to championship success - on this evidence - still looks steep.
Hatton Homage Inspires All-Manchester Contest
In the co-main event, Lyndon Arthur defeated Bradley Rea by close verdict in a excellent local rivalry fight to capture the European light heavyweight championship.
The stadium became quiet for a profoundly moving tribute before the fight as a bell ceremony sounded in remembrance of Manchester's own Ricky Hatton, who succumbed at age 46 in last month.
It was the first major televised boxing event in the urban center since Hatton's death. As the final chime disappeared, the silence gave way to a shout of "only one Hatton".
The action during the bout equaled the feeling. The eventual winner was sent to the canvas by a powerful punch squarely on the face in the initial stage, getting up unsteadily to his footing on the eight count.
But the red-colored equipment of the fighter soon came forward again. Across the ring, Rea - in opposing blue - was damaged early, heavy swelling forming under his eye as the fighters traded powerful shots.
The challenger, 27, delivered effective strikes but Arthur, 34, responded in kind with effective uppercuts as the intensity seldom decreased over 12 rounds.
The victor edged the decision with scoring tallies of even score, close margin and 115-112, but each competitor were determined and courageous, all the qualities their hero Hatton stood for.
