British light-heavyweight Buatsi made a winning yet disappointing start to life under new promoters with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's punch output appeared to earn him a judges' verdict in a close ten-round contest at the boxing arena.
But the challenger had his moments, connecting with powerful individual punches in a contest where the techniques never quite clicked, with frequent clinching disrupting the fight.
Two judges had it 96-94 to Buatsi, with the remaining official a even score.
"It wasn't my best display but what defines champions? They succeed," Buatsi commented in the ring as he was faced boos from the crowd.
The British fighter got back to winning after his maiden career setback - an memorable fight with Callum Smith in last winter - to secure a 20th pro success.
Some ringside observers felt Parker, thirty-one, should have been awarded the victory but the British boxer suffered the second setback of his 28-bout career.
The Champion Claims Triumph in Dull Match
The fighter's advancement has slowed in recent years through management issues and long spells of lack of fights.
Once tipped as the next star of the British fight scene, he now is positioned trying to fulfil that early promise - perhaps in what feels like a final roll of the dice - under recent support.
He opened tentatively, with both competitors prepared to be aggressive in a calculated opening few rounds.
The challenger, whose single earlier setback came at super middleweight against his former opponent in two years ago after damaging his hand mid-fight, was participating in his second fight at light-heavyweight.
By the middle rounds, the underdog had stayed in contention, creating difficulties for Buatsi, who worked behind a tight guard to edge the more effective stanzas.
The spectators' acceptance decreased because of constant clinching, with Parker slipping to the canvas several times during close exchanges.
The underdog ended stronger, but multiple periods were difficult to score. Although, previous titleholder Carl Frampton - providing analysis for the broadcast network - had it particularly wide for Parker, scoring for Buatsi just only one stanza.
Buatsi advances, but with the likes of hard hitter David Benavidez, and Eastern European fighter Bivol dominating the weight class, the journey to titles - judging by this showing - still seems difficult.
Hatton Tribute Motivates Local Rivalry Contest
In the secondary fight, Lyndon Arthur beat Bradley Rea by split-decision in a outstanding all-Manchester fight to win the European light heavyweight belt.
The arena became quiet for a deeply poignant homage before the fight as a bell ceremony tolled in memory of the city's native Hatton, who died at age 46 in last month.
It was the premier televised fight night in the city since the passing of Hatton. As the last bell ended, the stillness became a shout of "there's just one Hatton".
The fighting inside the ropes matched the emotion. The eventual winner was knocked down by a significant blow squarely on the jaw in the early round, rising shakily to his position on the eight count.
But the red-colored shorts of the fighter soon came forward again. From the other corner, the opponent - in rival City blue - was damaged early, significant bruising developing under his face as the duo traded powerful shots.
Rea, 27, delivered effective strikes but Arthur, thirty-four, matched the intensity with powerful upward punches as the pace hardly diminished over the full distance.
The victor barely secured the result with scoring tallies of draw, 115-113 and clearer margin, but the two athletes were determined and brave, everything their inspiration the legend stood for.
