British light-heavyweight Buatsi earned a win yet unimpressive start to his career under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's punch output likely gained him a judges' verdict in a competitive ten-round contest at the boxing arena.
But Parker landed significant shots, connecting with powerful single shots in a contest where the styles didn't complement each other, with excessive holding spoiling the contest.
The officials scored it 96-94 for to Buatsi, with the remaining official a 95-95.
"It wasn't my greatest showing but how do champions respond? They win," the victor commented in the arena as he was faced disapproval from the audience.
The British fighter bounced back after his first professional defeat - an thrilling contest with his previous opponent in February - to claim a 20th pro success.
Some ringside observers thought Parker, thirty-one, merited the victory but the British boxer endured the second defeat of his 28-fight professional journey.
The Champion Secures Win in Uneventful Affair
Buatsi's progress has plateaued in recent times through contract problems and long spells of lack of fights.
Once tipped as the future of the British fight scene, he now is positioned trying to fulfil that early promise - maybe in what seems like a last chance - under recent support.
He began cautiously, with both competitors ready to be aggressive in a cagey initial rounds.
The challenger, whose sole prior loss came at the lower weight class against his former opponent in 2022 after suffering a hand injury in the contest, was participating in his second appearance at light-heavyweight.
By the halfway stage, the underdog had made it competitive, creating difficulties for the favorite, who utilized a tight guard to barely take the better periods.
The audience's tolerance diminished during frequent holding, with the challenger slipping to the canvas multiple occasions during clinches.
Parker ended stronger, but many rounds were difficult to score. However, previous titleholder Carl Frampton - providing analysis for Dazn - had it strongly leaning for the challenger, awarding Buatsi just one round.
The victor moves on, but with the likes of power puncher Benavidez, and Russian star Dmitry Bivol leading the category, the path to championship success - on this evidence - still seems difficult.
Ricky Hatton Memorial Fuels Manchester Derby Fight
In the secondary fight, Arthur overcame Rea by split-decision in a excellent local rivalry contest to win the European light-heavyweight championship.
The arena grew hushed for a deeply poignant tribute ahead of the contest as 10 bells tolled in remembrance of Manchester's own Hatton, who passed away aged 46 in September.
It was the first major televised fight night in the location since the passing of Hatton. As the concluding sound faded, the silence transitioned to a shout of "there's just one Ricky Hatton".
The action during the bout equaled the emotion. Arthur was knocked down by a powerful punch squarely on the face in the second round, getting up unsteadily to his footing on the count of eight.
But the red-colored equipment of the fighter soon came forward again. From the other corner, Rea - in competitive blue - was injured early, significant bruising forming under his eye as the pair traded powerful shots.
Rea, 27, connected with strong blows but Arthur, 34, responded in kind with effective uppercuts as the intensity seldom decreased over 12 rounds.
The victor barely secured the verdict with judges scorecards of draw, narrow lead and wider gap, but the two athletes were persistent and full of heart, exactly what their idol Hatton represented.
