UK light-heavyweight Buatsi made a winning yet underwhelming debut to his career under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's activity level likely gained him a split decision in a tight 10-round contest at the Manchester venue.
But the challenger landed significant shots, connecting with powerful single shots in a contest where the techniques didn't complement each other, with frequent clinching disrupting the contest.
The officials judged it 96-94 for to Buatsi, with the third a 95-95 draw.
"It wasn't my best performance but what defines champions? They prevail," the victor said in the ringside as he was greeted with boos from the crowd.
The British fighter bounced back after his initial pro loss - an memorable fight with Callum Smith in February - to claim a twentieth professional win.
Several boxing experts believed the challenger, thirty-one, merited the decision but the Derbyshire fighter experienced the second setback of his 28-match professional journey.
Buatsi Earns Victory in Uneventful Encounter
Buatsi's progress has slowed in recent years through contract problems and long spells of lack of fights.
Previously predicted as the future of British boxing, he now is positioned trying to fulfil that early promise - possibly in what seems like a final roll of the dice - under new promotional backing.
He opened tentatively, with the two boxers ready to take risks in a cagey early stages.
The challenger, whose single earlier setback came at super-middleweight against his former opponent in two years ago after suffering a hand injury during the bout, was participating in his second appearance at the higher weight class.
By the fight's midpoint, Parker had made it competitive, making life awkward for Buatsi, who operated with a tight guard to edge the cleaner rounds.
The crowd's patience decreased during constant clinching, with the challenger falling to the floor various instances during clinches.
Parker ended stronger, but multiple periods were difficult to score. However, previous titleholder the boxing analyst - providing analysis for the broadcast network - had it significantly in favor for Parker, giving Buatsi just one round.
The victor moves on, but with the caliber of heavy hitter David Benavidez, and Russian star Bivol ruling the division, the path to championship success - based on this performance - still appears challenging.
Hatton Memorial Motivates All-Manchester Battle
In the co-main event, Arthur overcame Bradley Rea by split-decision in a outstanding all-Manchester battle to capture the European light-heavyweight title.
The arena fell silent for a deeply poignant homage before the fight as ten bells tolled in remembrance of the city's native Hatton, who succumbed aged 46 in recently.
It was the first major televised fight night in the urban center since the passing of Hatton. As the final chime ended, the stillness became a roar of "only one Ricky Hatton".
The action within the ring reflected the feeling. The eventual winner was floored by a significant blow flush on the jaw in the second round, getting up unsteadily to his footing on the eight count.
But the traditional red attire of the fighter soon came forward again. On the opposite side, the opponent - in opposing blue - was injured soon, heavy swelling appearing under his eye as the pair landed hard punches.
Rea, twenty-seven, connected with strong blows but the champion, 34, responded in kind with effective uppercuts as the action rarely dropped over 12 rounds.
The victor narrowly won the verdict with official scores of even score, close margin and 115-112, but the two athletes were determined and courageous, all the qualities their hero the legend stood for.
