UK light-heavyweight Buatsi secured a victory yet disappointing beginning to life under fresh promotional backing with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's punch output appeared to earn him a majority decision in a close ten-round fight at the boxing arena.
But the challenger landed significant shots, delivering effective clean blows in a match where the techniques failed to mesh, with excessive holding marring the fight.
The scoring judges judged it 96-94 to the winner, with the third a even score.
"It wasn't my finest showing but how do champions respond? They win," Buatsi said in the ringside as he was faced negative reactions from the audience.
The British fighter got back to winning after his first professional defeat - an thrilling contest with his previous opponent in February - to secure a 20th career victory.
Various analysts thought Parker, 31, should have been awarded the decision but the contender experienced the second setback of his 28-bout professional journey.
Buatsi Claims Triumph in Dull Affair
Buatsi's progress has slowed in recent years through management issues and extended periods of lack of fights.
Once tipped as the rising talent of the British fight scene, he now stands trying to achieve expectations - maybe in what feels like a final roll of the dice - under recent support.
He opened tentatively, with the two boxers ready to be aggressive in a cagey initial rounds.
Parker, whose sole prior loss came at super-middleweight against John Ryder in 2022 after suffering a hand injury mid-fight, was participating in his second fight at light-heavyweight.
By the middle rounds, Parker had stayed in contention, causing problems for the favorite, who operated with a solid defense to edge the cleaner periods.
The audience's tolerance wore thin during frequent holding, with Parker slipping to the canvas multiple occasions during clinches.
Parker closed well, but multiple periods were difficult to score. However, ex-champion Carl Frampton - working with Dazn - had it significantly in favor for the challenger, giving Buatsi just a single round.
The victor moves on, but with the caliber of heavy hitter Benavidez, and Eastern European fighter Bivol dominating the weight class, the journey to titles - judging by this showing - still looks steep.
Ricky Hatton Homage Fuels Local Rivalry Fight
In the secondary fight, Arthur defeated Bradley Rea by divided decision in a excellent all-Manchester battle to win the European light heavyweight title.
The venue fell silent for a extremely emotional tribute before the fight as ten bells tolled in remembrance of the city's native Hatton, who succumbed at age 46 in recently.
It was the initial significant broadcast boxing event in the urban center since Hatton's passing. As the last bell disappeared, the quiet became a roar of "there's just one Hatton".
The action inside the ropes matched the sentiment. The eventual winner was knocked down by a significant blow directly to the chin in the initial stage, getting up unsteadily to his footing on the eight count.
But the Manchester United-red equipment of the fighter soon advanced again. On the opposite side, the opponent - in opposing blue - was marked up soon, significant bruising appearing under his orbital area as the duo landed hard punches.
Rea, twenty-seven, delivered effective strikes but the champion, thirty-four, responded in kind with effective uppercuts as the intensity rarely dropped over twelve rounds.
The victor narrowly won the result with judges scorecards of 114-114, narrow lead and clearer margin, but each competitor were persistent and full of heart, everything their inspiration Hatton stood for.
