British light-heavyweight Buatsi earned a win yet disappointing beginning to life under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output likely gained him a majority decision in a competitive 10-round bout at the Manchester venue.
But Parker had his moments, connecting with powerful single shots in a contest where the styles didn't complement each other, with frequent clinching marring the action.
The scoring judges had it 96-94 in favor to Buatsi, with the remaining official a even score.
"It wasn't my best showing but how do champions respond? They prevail," Buatsi stated in the ringside as he was faced disapproval from the spectators.
The Londoner got back to winning after his first professional defeat - an thrilling contest with his previous opponent in February - to secure a 20th career victory.
Several boxing experts thought Parker, 31, deserved the victory but the contender suffered the second setback of his 28-fight career.
Buatsi Earns Win in Dull Match
His career development has slowed in recent years through management issues and long spells of inactivity.
Previously predicted as the future of the British fight scene, he now stands trying to realize his potential - maybe in what seems like a final roll of the dice - under fresh management.
He opened tentatively, with the two boxers ready to be aggressive in a cagey early stages.
Parker, whose only previous defeat came at super-middleweight against his former opponent in two years ago after breaking his hand during the bout, was making just his second bout at the higher weight class.
By the middle rounds, Parker had stayed in contention, causing problems for the favorite, who worked behind a solid defense to narrowly win the better stanzas.
The spectators' acceptance wore thin amid regular grabbing, with the challenger slipping to the canvas several times during close exchanges.
Parker finished the stronger, but several stanzas were difficult to score. Although, former world champion Carl Frampton - working with Dazn - had it strongly leaning for Parker, awarding Buatsi just one round.
The victor progresses, but with the caliber of heavy hitter Benavidez, and Russian star Bivol ruling the division, the road to world glory - on this evidence - still looks steep.
Ricky Hatton Homage Fuels Manchester Derby Contest
In the supporting bout, Lyndon Arthur defeated Rea by divided decision in a excellent local rivalry battle to win the continental championship.
The stadium became quiet for a deeply poignant homage ahead of the contest as ten bells rang in memory of Manchester's own Ricky Hatton, who died at age 46 in September.
It was the initial significant broadcast boxing event in the location since Hatton's death. As the final chime disappeared, the silence gave way to a chant of "only one Hatton".
The action within the ring matched the emotion. Arthur was floored by a significant blow squarely on the chin in the initial stage, getting up unsteadily to his feet on the eight count.
But the Manchester United-red equipment of the fighter soon came forward again. Across the ring, the opponent - in competitive blue - was damaged early, heavy swelling developing under his eye as the duo exchanged punishing blows.
The challenger, twenty-seven, connected with strong blows but the champion, thirty-four, fought fire with fire with powerful upward punches as the intensity seldom decreased over 12 rounds.
Arthur edged the verdict with judges scorecards of draw, narrow lead and 115-112, but both fighters were relentless and brave, exactly what their hero Hatton embodied.
