UK light-heavyweight Buatsi made a winning yet disappointing beginning to his career under recent management with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's punch output seemingly secured him a majority decision in a tight ten-round contest at the boxing arena.
But the challenger landed significant shots, connecting with powerful single shots in a fight where the techniques failed to mesh, with frequent clinching marring the fight.
The officials had it 96-94 to Buatsi, with the final judge a 95-95 draw.
"It wasn't my best display but how do champions respond? They prevail," the victor commented in the ringside as he was greeted with boos from the spectators.
The Londoner bounced back after his initial pro loss - an thrilling contest with Callum Smith in February - to secure a 20th career victory.
Various analysts believed the challenger, 31, deserved the decision but the contender endured the second defeat of his 28-match career.
The Champion Earns Victory in Uneventful Affair
The fighter's advancement has slowed in recent times through management issues and long spells of inactivity.
Once tipped as the next star of UK boxing, he now stands trying to fulfil that early promise - maybe in what appears to be a ultimate opportunity - under recent support.
He opened tentatively, with the two boxers willing to be aggressive in a cagey initial rounds.
Parker, whose sole prior loss came at super middleweight against John Ryder in 2022 after breaking his hand in the contest, was making just his second bout at light heavyweight.
By the fight's midpoint, Parker had stayed in contention, making life awkward for the favorite, who operated with a protective stance to narrowly win the cleaner stanzas.
The spectators' acceptance wore thin during regular grabbing, with Parker going down multiple occasions during close exchanges.
Parker closed well, but multiple periods were challenging to assess. Nevertheless, previous titleholder the boxing analyst - commentating on the broadcast network - had it particularly wide for Parker, giving Buatsi just one round.
The victor advances, but with the likes of hard hitter Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the road to world glory - on this evidence - still appears challenging.
Ricky Hatton Memorial Motivates Manchester Derby Fight
In the supporting bout, Arthur beat Rea by divided decision in a outstanding local rivalry fight to capture the European light heavyweight belt.
The venue grew hushed for a extremely emotional homage ahead of the contest as 10 bells sounded in remembrance of the city's native Hatton, who died aged 46 in September.
It was the premier televised match card in the city since the passing of Hatton. As the last bell disappeared, the silence transitioned to a chant of "there's only one Hatton".
The fighting inside the ropes reflected the feeling. Arthur was knocked down by a powerful punch directly to the chin in the second round, getting up unsteadily to his position on the referee's count.
But the traditional red attire of Arthur soon came forward again. From the other corner, Rea - in opposing blue - was marked up quickly, noticeable damage developing under his eye as the pair traded hard punches.
Rea, 27, landed power punches but the champion, 34, matched the intensity with powerful upward punches as the pace rarely dropped over the full distance.
Arthur barely secured the verdict with judges scorecards of even score, 115-113 and 115-112, but each competitor were persistent and full of heart, all the qualities their hero the legend represented.
