UK light-heavyweight Buatsi earned a win yet unimpressive beginning to his career under fresh promotional backing with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level appeared to earn him a split decision in a competitive ten-round bout at the Co-op Live Arena.
But Parker found success, landing some telling individual punches in a fight where the techniques didn't complement each other, with excessive holding marring the action.
The scoring judges had it 96-94 in favor to Buatsi, with the final judge a 95-95.
"It wasn't my finest display but what do champions do? They prevail," the victor said in the ringside as he was faced disapproval from the crowd.
The Londoner 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 the challenger, 31, should have been awarded the victory but the British boxer suffered the second loss of his 28-bout professional journey.
Buatsi Secures Victory in Uneventful Affair
The fighter's advancement has stalled in recent years through contract problems and extended periods of inactivity.
Once tipped as the next star of the British fight scene, he now is positioned trying to fulfil that early promise - perhaps in what appears to be a last chance - under recent support.
He started carefully, with the two boxers prepared to be aggressive in a tentative initial rounds.
Parker, whose sole prior loss came at super middleweight against his former opponent in two years ago after breaking his hand in the contest, was participating in his second appearance at light-heavyweight.
By the halfway stage, Parker had stayed in contention, causing problems for Buatsi, who utilized a protective stance to narrowly win the better rounds.
The spectators' acceptance wore thin because of frequent holding, with Parker slipping to the canvas several times during clinches.
The underdog closed well, but several stanzas were difficult to score. Nevertheless, former world champion Carl Frampton - providing analysis for Dazn - had it strongly leaning for Parker, scoring for Buatsi just a single round.
The victor advances, but with the likes of heavy hitter David Benavidez, and Eastern European fighter Bivol leading the category, the journey to titles - on this evidence - still seems difficult.
Ricky Hatton Memorial Motivates Local Rivalry Battle
In the secondary fight, Lyndon Arthur overcame Rea by divided decision in a terrific Manchester vs Manchester battle to capture the continental championship.
The venue fell silent for a profoundly moving memorial before the fight as ten bells rang in honor of the city's native Hatton, who died aged 46 in September.
It was the first major televised boxing event in the location since the passing of Hatton. As the last bell ended, the stillness transitioned to a shout of "there's just one Ricky Hatton".
The competition within the ring reflected the feeling. The eventual winner was knocked down by a significant blow flush on the face in the early round, standing uncertainly to his position on the eight count.
But the Manchester United-red equipment of Arthur soon pressed ahead again. From the other corner, Rea - in opposing blue - was marked up soon, significant bruising forming under his eye as the fighters landed powerful shots.
Rea, twenty-seven, connected with strong blows but Arthur, thirty-four, matched the intensity with stinging uppercuts as the intensity rarely dropped over twelve rounds.
Arthur edged the result with scoring tallies of 114-114, close margin and wider gap, but both fighters were determined and courageous, everything their idol Hatton stood for.
