UK light-heavyweight Buatsi earned a win yet disappointing beginning to his career under new promoters with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output likely gained him a judges' verdict in a close ten-round contest at the Manchester venue.
But the challenger had his moments, connecting with powerful individual punches in a contest where the approaches never quite clicked, with frequent clinching spoiling the action.
Two judges judged it 96-94 in favor to Buatsi, with the final judge a even score.
"It wasn't my best performance but how do champions respond? They win," the victor commented in the ringside as he was faced negative reactions from the audience.
The British fighter got back to winning after his initial pro loss - an epic battle with his previous opponent in last winter - to claim a twentieth professional win.
Various analysts thought Parker, 31, deserved the win but the Derbyshire fighter endured the second loss of his 28-fight professional journey.
Buatsi Claims Victory in Uneventful Match
Buatsi's progress has slowed in recent years through promotional disputes and extended periods of lack of fights.
Previously predicted as the next star of the British fight scene, he now finds himself trying to realize his potential - perhaps in what seems like a final roll of the dice - under recent support.
He opened tentatively, with the two boxers willing to be aggressive in a tentative early stages.
The challenger, whose single earlier setback came at the lower weight class against John Ryder in two years ago after suffering a hand injury during the bout, was making just his second fight at light-heavyweight.
By the fight's midpoint, the underdog had stayed in contention, causing problems for Buatsi, who operated with a protective stance to edge the better periods.
The spectators' acceptance decreased during frequent holding, with the challenger falling to the floor various instances during clinches.
Parker ended stronger, but many rounds were hard to judge. Although, previous titleholder the boxing analyst - working with the broadcast network - had it particularly wide for Parker, awarding Buatsi just a single round.
Buatsi progresses, but with the likes of heavy hitter David Benavidez, and Russian champion Bivol leading the category, the path to championship success - based on this performance - still appears challenging.
Ricky Hatton Tribute Motivates All-Manchester Fight
In the co-main event, Lyndon Arthur defeated Rea by close verdict in a outstanding Manchester vs Manchester contest to win the continental championship.
The stadium grew hushed for a profoundly moving homage ahead of the contest as a bell ceremony sounded in memory of the city's native Hatton, who died 46 years old in September.
It was the first major televised fight night in the urban center since Hatton's passing. As the concluding sound disappeared, the quiet became a roar of "only one Ricky Hatton".
The fighting during the bout matched the sentiment. The eventual winner was knocked down by a left hook flush on the chin in the second round, getting up unsteadily to his feet on the count of eight.
But the Manchester United-red attire of the fighter soon came forward again. From the other corner, the opponent - in rival City blue - was marked up soon, significant bruising developing under his eye as the fighters traded powerful shots.
Rea, twenty-seven, connected with strong blows but Arthur, 34, fought fire with fire with effective uppercuts as the intensity rarely dropped over twelve rounds.
Arthur barely secured the decision with official scores of 114-114, 115-113 and wider gap, but the two athletes were persistent and courageous, exactly what their inspiration Hatton embodied.
