UK light heavyweight Buatsi made a winning yet disappointing start to his career under fresh promotional backing with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level appeared to earn him a majority decision in a tight 10-round fight at the Manchester venue.
But the challenger landed significant shots, delivering effective single shots in a fight where the techniques failed to mesh, with excessive holding disrupting the contest.
The officials had it 96-94 in favor to Buatsi, with the final judge a 95-95 draw.
"It wasn't my greatest showing but what do champions do? They succeed," the victor stated in the ring as he was faced boos from the spectators.
The Londoner bounced back after his first professional defeat - an thrilling contest with his previous opponent in last winter - to earn a 20th pro success.
Various analysts believed Parker, 31, merited the victory but the British boxer suffered the second setback of his 28-bout career.
The Champion Earns Win in Slow Match
His career development has stalled in the past few years through promotional disputes and considerable time of inactivity.
Previously predicted as the future of the British fight scene, he now is positioned trying to fulfil that early promise - possibly in what seems like a final roll of the dice - under new promotional backing.
He started carefully, with neither fighter willing to be aggressive in a calculated early stages.
Parker, whose single earlier setback came at super-middleweight against John Ryder in two years ago after suffering a hand injury during the bout, was making just his second bout at the higher weight class.
By the middle rounds, the underdog had made it competitive, creating difficulties for Buatsi, who worked behind a tight guard to narrowly win the better periods.
The audience's tolerance wore thin amid regular grabbing, with the challenger slipping to the canvas various instances during clinches.
The underdog closed well, but many rounds were challenging to assess. However, previous titleholder Carl Frampton - providing analysis for the broadcast network - had it particularly wide for the challenger, scoring for Buatsi just only one stanza.
The victor progresses, but with the likes of heavy hitter David Benavidez, and Eastern European fighter Bivol ruling the division, the road to world glory - on this evidence - still appears challenging.
Ricky Hatton Tribute Inspires Manchester Derby Fight
In the supporting bout, Lyndon Arthur overcame Bradley Rea by close verdict in a outstanding all-Manchester battle to secure the European light heavyweight belt.
The arena grew hushed for a extremely emotional homage ahead of the contest as 10 bells rang in remembrance of the city's native Ricky Hatton, who passed away 46 years old in recently.
It was the initial significant broadcast fight night in the city since Hatton's death. As the concluding sound disappeared, the silence became a chant of "there's only one Ricky Hatton".
The fighting inside the ropes matched the feeling. The eventual winner was sent to the canvas by a significant blow flush on the face in the initial stage, rising shakily to his footing on the referee's count.
But the Manchester United-red equipment of Arthur soon pressed ahead again. Across the ring, the opponent - in rival City blue - was damaged quickly, heavy swelling forming under his orbital area as the pair exchanged powerful shots.
Rea, twenty-seven, delivered effective strikes but Arthur, thirty-four, responded in kind with effective uppercuts as the intensity hardly diminished over the full distance.
The victor narrowly won the decision with official scores of even score, 115-113 and clearer margin, but the two athletes were persistent and courageous, exactly what their hero Hatton stood for.
