UK light heavyweight Buatsi made a winning yet unimpressive beginning to his career under recent management with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's work rate seemingly secured him a judges' verdict in a close 10-round bout at the Manchester venue.
But Parker had his moments, landing some telling individual punches in a fight where the styles never quite clicked, with frequent clinching marring the action.
Two judges judged it 96-94 to Buatsi, with the final judge a 95-95.
"It wasn't my best showing but what do champions do? They win," Buatsi stated in the ringside as he was faced disapproval from the spectators.
The Londoner bounced back after his initial pro loss - an memorable fight with Callum Smith in last winter - to claim a twentieth professional win.
Various analysts believed the challenger, thirty-one, deserved the victory but the contender suffered the second defeat of his 28-fight professional journey.
The Champion Earns Win in Uneventful Encounter
Buatsi's progress has stalled in the past few years through contract problems and extended periods of inactivity.
Once tipped as the next star of the British fight scene, he now stands trying to achieve expectations - maybe in what appears to be a ultimate opportunity - under new promotional backing.
He started carefully, with the two boxers ready to be aggressive in a tentative initial rounds.
The challenger, whose sole prior loss came at super-middleweight against John Ryder in two years ago after damaging his hand mid-fight, was making just his second appearance at light-heavyweight.
By the middle rounds, the underdog had kept it close, causing problems for Buatsi, who utilized a protective stance to narrowly win the cleaner periods.
The audience's tolerance diminished during constant clinching, with the challenger slipping to the canvas multiple occasions during clinches.
Parker closed well, but several stanzas were hard to judge. Although, former world champion Carl Frampton - commentating on Dazn - had it strongly leaning for the challenger, scoring for Buatsi just a single round.
Buatsi advances, but with the likes of heavy hitter David Benavidez, and Russian champion Dmitry Bivol leading the category, the journey to titles - on this evidence - still seems difficult.
Hatton Tribute Motivates Manchester Derby Fight
In the secondary fight, Lyndon Arthur defeated Bradley Rea by split-decision in a terrific all-Manchester contest to capture the European light heavyweight championship.
The stadium became quiet for a extremely emotional homage before the fight as a bell ceremony tolled in honor of the city's native Ricky Hatton, who succumbed at age 46 in last month.
It was the initial significant broadcast fight night in the location since Hatton's death. As the last bell faded, the quiet gave way to a shout of "there's only one Hatton".
The competition within the ring reflected the feeling. Arthur was knocked down by a significant blow flush on the chin in the early round, standing uncertainly to his feet on the eight count.
But the red-colored equipment of Arthur soon came forward again. From the other corner, Rea - in competitive blue - was damaged early, significant bruising forming under his face as the duo exchanged punishing blows.
Rea, twenty-seven, landed power punches but the champion, thirty-four, responded in kind with stinging uppercuts as the pace hardly diminished over 12 rounds.
The victor edged the result with scoring tallies of draw, 115-113 and clearer margin, but both fighters were determined and full of heart, exactly what their inspiration Hatton embodied.
