UK light heavyweight Buatsi earned a win yet disappointing debut to life under new promoters with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level appeared to earn him a split decision in a tight ten-round contest at the Manchester venue.
But the challenger had his moments, connecting with powerful clean blows in a fight where the approaches didn't complement each other, with constant grabbing disrupting the contest.
The officials scored it 96-94 in favor to the winner, with the third a 95-95 draw.
"It wasn't my greatest showing but what do champions do? They prevail," the victor commented in the arena as he was met by boos from the spectators.
The British fighter bounced back after his maiden career setback - an epic battle with his previous opponent in last winter - to earn a 20th career victory.
Several boxing experts felt the challenger, thirty-one, merited the victory but the contender suffered the second loss of his 28-match career.
The Champion Secures Win in Uneventful Match
The fighter's advancement has plateaued in recent years through management issues and considerable time of inactivity.
Previously predicted as the rising talent of British boxing, he now finds himself trying to achieve expectations - possibly in what seems like a final roll of the dice - under recent support.
He started carefully, with the two boxers willing to be aggressive in a cagey early stages.
The challenger, whose only previous defeat came at super middleweight against John Ryder in 2022 after damaging his hand mid-fight, was competing in only his second appearance at the higher weight class.
By the middle rounds, the underdog had kept it close, causing problems for Buatsi, who operated with a solid defense to narrowly win the cleaner rounds.
The crowd's patience diminished during frequent holding, with Parker going down various instances during close exchanges.
Parker ended stronger, but several stanzas were difficult to score. However, former world champion Carl Frampton - working with the broadcast network - had it significantly in favor for Parker, awarding Buatsi just only one stanza.
The victor moves on, but with the likes of power puncher Benavidez, and Russian champion Dmitry Bivol leading the category, the path to championship success - judging by this showing - still appears challenging.
Hatton Tribute Inspires Manchester Derby Battle
In the co-main event, Arthur defeated Bradley Rea by divided decision in a terrific all-Manchester contest to capture the European light-heavyweight championship.
The venue grew hushed for a profoundly moving tribute before the fight as ten bells sounded in honor of the city's native Ricky Hatton, who succumbed aged 46 in September.
It was the first major televised boxing event in the location since the passing of Hatton. As the concluding sound disappeared, the stillness gave way to a shout of "there's just one Ricky Hatton".
The action during the bout equaled the emotion. Arthur was floored by a left hook flush on the jaw in the initial stage, standing uncertainly to his feet on the count of eight.
But the traditional red equipment of Arthur soon pressed ahead again. On the opposite side, the opponent - in rival City blue - was damaged early, noticeable damage developing under his orbital area as the duo exchanged punishing blows.
The challenger, 27, connected with strong blows but the champion, thirty-four, fought fire with fire with effective uppercuts as the intensity hardly diminished over the full distance.
The victor narrowly won the decision with judges scorecards of 114-114, close margin and wider gap, but both fighters were persistent and brave, everything their hero the legend represented.
