UK light heavyweight Buatsi earned a win yet disappointing start to life under recent management with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output likely gained him a judges' verdict in a close 10-round bout at the boxing arena.
But the challenger had his moments, delivering effective single shots in a contest where the approaches never quite clicked, with frequent clinching spoiling the fight.
Two judges judged it 96-94 to Buatsi, with the remaining official a 95-95.
"It wasn't my finest showing but what do champions do? They win," the victor said in the ringside as he was greeted with boos from the audience.
The Londoner bounced back after his maiden career setback - an thrilling contest with his previous opponent in last winter - to secure a 20th pro success.
Several boxing experts believed the challenger, 31, merited the victory but the British boxer suffered the second loss of his 28-fight professional journey.
The Champion Earns Triumph in Uneventful Match
His career development has plateaued in recent years through management issues and long spells of lack of fights.
Once tipped as the rising talent of UK boxing, he now is positioned trying to achieve expectations - possibly in what seems like a final roll of the dice - under recent support.
He started carefully, with both competitors ready to take risks in a cagey opening few rounds.
The challenger, whose single earlier setback came at super middleweight against John Ryder in 2022 after suffering a hand injury in the contest, was making just his second appearance at light-heavyweight.
By the fight's midpoint, the underdog had made it competitive, making life awkward for the favorite, who utilized a tight guard to edge the more effective stanzas.
The audience's tolerance wore thin because of regular grabbing, with Parker slipping to the canvas various instances during grappling.
Parker closed well, but many rounds were hard to judge. However, ex-champion the boxing analyst - providing analysis for Dazn - had it particularly wide for the challenger, scoring for Buatsi just a single round.
The victor moves on, but with the caliber of heavy hitter David Benavidez, and Eastern European fighter Bivol leading the category, the road to world glory - based on this performance - still appears challenging.
Ricky Hatton Tribute Motivates All-Manchester Battle
In the co-main event, Arthur beat Bradley Rea by split-decision in a outstanding Manchester vs Manchester fight to capture the European light heavyweight championship.
The stadium grew hushed for a extremely emotional tribute prior to the bout as 10 bells rang in honor of Manchester's own Hatton, who succumbed aged 46 in last month.
It was the premier televised boxing event in the location since Hatton's passing. As the final chime ended, the silence became a roar of "there's just one Hatton".
The fighting within the ring matched the feeling. The eventual winner was floored by a significant blow squarely on the chin in the second round, rising shakily to his position on the count of eight.
But the Manchester United-red attire of Arthur soon advanced again. From the other corner, Rea - in opposing blue - was marked up quickly, heavy swelling developing under his orbital area as the fighters landed punishing blows.
Rea, 27, delivered effective strikes but Arthur, thirty-four, fought fire with fire with stinging uppercuts as the action rarely dropped over twelve rounds.
Arthur barely secured the result with scoring tallies of 114-114, narrow lead and wider gap, but the two athletes were determined and full of heart, all the qualities their idol the legend stood for.
