UK light-heavyweight Buatsi earned a win yet underwhelming start to his career under fresh promotional backing with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's work rate seemingly secured him a judges' verdict in a tight 10-round bout at the Manchester venue.
But the challenger landed significant shots, landing some telling individual punches in a fight where the techniques never quite clicked, with excessive holding marring the action.
Two judges had it 96-94 for to Buatsi, with the third a even score.
"It wasn't my finest performance but what defines champions? They succeed," the victor said in the ringside as he was met by disapproval from the crowd.
The Londoner got back to winning after his maiden career setback - an epic battle with his previous opponent in February - to claim a twentieth professional win.
Some ringside observers felt Parker, thirty-one, merited the win but the contender experienced the second setback of his 28-match professional journey.
Buatsi Earns Triumph in Uneventful Affair
Buatsi's progress has stalled in recent times through management issues and considerable time of inactivity.
Once tipped as the future of the British fight scene, he now stands trying to achieve expectations - maybe in what appears to be a final roll of the dice - under new promotional backing.
He started carefully, with the two boxers willing to be aggressive in a cagey initial rounds.
Parker, whose single earlier setback came at the lower weight class against John Ryder in 2022 after suffering a hand injury mid-fight, was competing in only his second fight at the higher weight class.
By the fight's midpoint, the underdog had stayed in contention, making life awkward for the favorite, who worked behind a solid defense to edge the better stanzas.
The crowd's patience wore thin because of regular grabbing, with the challenger falling to the floor various instances during close exchanges.
The underdog finished the stronger, but many rounds were challenging to assess. Although, ex-champion the boxing analyst - commentating on Dazn - had it significantly in favor for the challenger, awarding Buatsi just one round.
Buatsi moves on, but with the caliber of hard hitter David Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the path to championship success - on this evidence - still looks steep.
Hatton Memorial Inspires Manchester Derby Battle
In the co-main event, Arthur overcame Bradley Rea by split-decision in a excellent Manchester vs Manchester fight to capture the continental belt.
The stadium became quiet for a extremely emotional memorial before the fight as 10 bells tolled in remembrance of Manchester's own Ricky Hatton, who died 46 years old in last month.
It was the first major televised boxing event in the location since the passing of Hatton. As the final chime ended, the stillness transitioned to a shout of "there's only one Ricky Hatton".
The fighting inside the ropes reflected the sentiment. Arthur was sent to the canvas by a left hook flush on the jaw in the initial stage, standing uncertainly to his feet on the count of eight.
But the Manchester United-red shorts of the fighter soon advanced again. From the other corner, Rea - in rival City blue - was damaged quickly, significant bruising developing under his eye as the fighters exchanged powerful shots.
The challenger, twenty-seven, connected with strong blows but Arthur, thirty-four, responded in kind with effective uppercuts as the pace rarely dropped over twelve rounds.
Arthur edged the verdict with judges scorecards of even score, 115-113 and clearer margin, but both fighters were persistent and courageous, exactly what their idol the legend embodied.
