British light heavyweight Buatsi secured a victory yet underwhelming start to life under fresh promotional backing with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level likely gained him a majority decision in a tight ten-round fight at the Co-op Live Arena.
But Parker landed significant shots, delivering effective single shots in a fight where the approaches failed to mesh, with excessive holding spoiling the action.
The scoring judges judged it 96-94 to the winner, with the third a even score.
"It wasn't my finest performance but what defines champions? They prevail," the victor commented in the ring as he was met by negative reactions from the spectators.
The British fighter got back to winning after his initial pro loss - an thrilling contest with Callum Smith in February - to claim a 20th pro success.
Some ringside observers felt the challenger, 31, should have been awarded the win but the contender endured the second setback of his 28-fight career.
Buatsi Earns Victory in Dull Encounter
The fighter's advancement has stalled in the past few years through promotional disputes and long spells of lack of fights.
Once tipped as the future of British boxing, he now stands trying to fulfil that early promise - perhaps in what feels like a last chance - under recent support.
He started carefully, with neither fighter willing to overcommit in a tentative early stages.
The challenger, whose sole prior loss came at super-middleweight against his former opponent in two years ago after suffering a hand injury in the contest, was making just his second appearance at light heavyweight.
By the fight's midpoint, Parker had kept it close, creating difficulties for the favorite, who worked behind a protective stance to barely take the cleaner periods.
The crowd's patience decreased during regular grabbing, with Parker slipping to the canvas various instances during close exchanges.
The underdog closed well, but multiple periods were challenging to assess. Nevertheless, previous titleholder the boxing analyst - providing analysis for the broadcast network - had it significantly in favor for Parker, giving Buatsi just one round.
The victor advances, but with the caliber of heavy hitter David Benavidez, and Russian star Bivol ruling the division, the road to world glory - based on this performance - still seems difficult.
Hatton Homage Motivates Local Rivalry Fight
In the supporting bout, Lyndon Arthur overcame Bradley Rea by close verdict in a terrific all-Manchester contest to secure the European light-heavyweight belt.
The arena became quiet for a extremely emotional memorial before the fight as a bell ceremony rang in honor of the city's native Ricky Hatton, who passed away 46 years old in September.
It was the first major televised boxing event in the location since Hatton's death. As the final chime disappeared, the quiet gave way to a shout of "only one Hatton".
The fighting inside the ropes matched the feeling. The eventual winner was knocked down by a powerful punch flush on the face in the second round, standing uncertainly to his position on the referee's count.
But the traditional red equipment of Arthur soon came forward again. Across the ring, Rea - in rival City blue - was damaged soon, noticeable damage appearing under his face as the duo exchanged punishing blows.
The challenger, twenty-seven, landed power punches but Arthur, thirty-four, matched the intensity with stinging uppercuts as the pace hardly diminished over the full distance.
The victor narrowly won the decision with judges scorecards of 114-114, close margin and 115-112, but each competitor were persistent and courageous, exactly what their inspiration Hatton embodied.
