UK light heavyweight Buatsi secured a victory yet disappointing beginning to life under new promoters with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's punch output appeared to earn him a majority decision in a tight ten-round fight at the Co-op Live Arena.
But the challenger found success, connecting with powerful clean blows in a match where the techniques never quite clicked, with excessive holding spoiling the fight.
The scoring judges judged it 96-94 to the winner, with the remaining official a 95-95 draw.
"It wasn't my greatest display but what do champions do? They succeed," the victor commented in the arena as he was faced negative reactions from the spectators.
The British fighter bounced back after his maiden career setback - an thrilling contest with his previous opponent in last winter - to claim a twentieth professional win.
Various analysts felt Parker, 31, should have been awarded the decision but the contender endured the second defeat of his 28-fight career.
The Champion Secures Victory in Slow Match
The fighter's advancement has slowed in recent times through promotional disputes and extended periods of lack of fights.
Previously predicted as the rising talent of British boxing, he now stands trying to fulfil that early promise - possibly in what seems like a ultimate opportunity - under recent support.
He started carefully, with the two boxers willing to take risks in a calculated initial rounds.
Parker, whose sole prior loss came at super-middleweight against his former opponent in 2022 after breaking his hand during the bout, was competing in only his second fight at light-heavyweight.
By the fight's midpoint, the underdog had stayed in contention, causing problems for the favorite, who utilized a solid defense to narrowly win the better periods.
The crowd's patience diminished because of constant clinching, with the challenger going down various instances during grappling.
Parker ended stronger, but several stanzas were difficult to score. However, former world champion Carl Frampton - commentating on the broadcast network - had it strongly leaning for the challenger, giving Buatsi just a single round.
The victor progresses, but with the caliber of heavy hitter David Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the road to world glory - on this evidence - still seems difficult.
Hatton Memorial Inspires All-Manchester Fight
In the supporting bout, Lyndon Arthur overcame Rea by split-decision in a excellent local rivalry battle to secure the continental championship.
The stadium became quiet for a extremely emotional homage ahead of the contest as ten bells sounded in honor of the city's native Ricky Hatton, who passed away at age 46 in recently.
It was the first major televised fight night in the city since Hatton's death. As the concluding sound disappeared, the quiet transitioned to a chant of "there's only one Ricky Hatton".
The competition inside the ropes equaled the emotion. The eventual winner was floored by a significant blow flush on the face in the second round, standing uncertainly to his feet on the referee's count.
But the red-colored attire of the fighter soon advanced again. From the other corner, the opponent - in competitive blue - was damaged early, heavy swelling developing under his face as the pair exchanged punishing blows.
The challenger, 27, connected with strong blows but Arthur, 34, responded in kind with stinging uppercuts as the intensity seldom decreased over 12 rounds.
The victor narrowly won the verdict with judges scorecards of 114-114, narrow lead and wider gap, but each competitor were relentless and courageous, everything their hero Hatton stood for.
