British light heavyweight Buatsi earned a win yet underwhelming beginning to his career under recent management with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level likely gained him a judges' verdict in a close 10-round fight at the Manchester venue.
But the challenger landed significant shots, landing some telling clean blows in a fight where the styles didn't complement each other, with excessive holding marring the contest.
Two judges judged it 96-94 in favor to the winner, with the third a 95-95.
"It wasn't my best showing but what defines champions? They win," the victor said in the ringside as he was faced disapproval from the audience.
The British fighter returned to winning ways after his first professional defeat - an memorable fight with Callum Smith in last winter - to claim a 20th career victory.
Several boxing experts felt Parker, 31, deserved the win but the contender experienced the second defeat of his 28-bout career.
Buatsi Earns Triumph in Slow Encounter
The fighter's advancement has slowed in the past few years through promotional disputes and considerable time of inactivity.
Once tipped as the future of UK boxing, he now stands trying to achieve expectations - perhaps in what feels like a final roll of the dice - under fresh management.
He opened tentatively, with both competitors willing to take risks in a calculated early stages.
The challenger, whose sole prior loss came at super-middleweight against his former opponent in two years ago after breaking his hand during the bout, was participating in his second appearance at light-heavyweight.
By the fight's midpoint, Parker had kept it close, causing problems for the favorite, who operated with a solid defense to narrowly win the more effective rounds.
The spectators' acceptance diminished because of frequent holding, with the challenger going down several times during close exchanges.
Parker closed well, but many rounds were challenging to assess. However, ex-champion Carl Frampton - working with the broadcast network - had it particularly wide for Parker, awarding Buatsi just one round.
Buatsi progresses, but with the presence of heavy hitter David Benavidez, and Russian champion Bivol leading the category, the road to world glory - based on this performance - still seems difficult.
Hatton Tribute Motivates Local Rivalry Battle
In the co-main event, Lyndon Arthur beat Rea by close verdict in a terrific all-Manchester battle to capture the continental championship.
The venue grew hushed for a deeply poignant tribute prior to the bout as 10 bells sounded in remembrance of Manchester's own Ricky Hatton, who succumbed 46 years old in recently.
It was the initial significant broadcast boxing event in the urban center since the passing of Hatton. As the last bell ended, the silence gave way to a roar of "there's only one Hatton".
The competition within the ring equaled the emotion. The eventual winner was floored by a powerful punch squarely on the face in the initial stage, rising shakily to his feet on the eight count.
But the Manchester United-red attire of Arthur soon pressed ahead again. From the other corner, Rea - in opposing blue - was marked up quickly, significant bruising forming under his orbital area as the duo exchanged hard punches.
The challenger, twenty-seven, delivered effective strikes but Arthur, 34, responded in kind with effective uppercuts as the intensity rarely dropped over the full distance.
Arthur edged the decision with scoring tallies of even score, close margin and wider gap, but both fighters were persistent and full of heart, everything their idol the legend stood for.
