UK light-heavyweight Buatsi secured a victory yet underwhelming beginning to life under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level seemingly secured him a judges' verdict in a close ten-round contest at the Manchester venue.
But Parker found success, delivering effective single shots in a match where the styles didn't complement each other, with frequent clinching marring the fight.
The officials had it 96-94 for to Buatsi, with the remaining official a even score.
"It wasn't my best display but what do champions do? They succeed," Buatsi commented in the ringside as he was met by negative reactions from the spectators.
The British fighter bounced back after his first professional defeat - an thrilling contest with his previous opponent in February - to earn a twentieth professional win.
Various analysts thought Parker, thirty-one, should have been awarded the decision but the British boxer suffered the second loss of his 28-bout career.
The Champion Secures Triumph in Uneventful Affair
His career development has stalled in recent years through management issues and considerable time of inactivity.
Earlier forecast as the rising talent of UK boxing, he now stands trying to fulfil that early promise - perhaps in what seems like a ultimate opportunity - under recent support.
He began cautiously, with the two boxers prepared to take risks in a cagey opening few rounds.
The challenger, whose single earlier setback came at super-middleweight against John Ryder in two years ago after damaging his hand during the bout, was making just his second bout at the higher weight class.
By the halfway stage, Parker had kept it close, making life awkward for Buatsi, who utilized a protective stance to barely take the more effective rounds.
The spectators' acceptance decreased because of constant clinching, with the challenger slipping to the canvas several times during grappling.
The underdog ended stronger, but several stanzas were challenging to assess. Nevertheless, previous titleholder Carl Frampton - providing analysis for Dazn - had it particularly wide for the challenger, awarding Buatsi just one round.
Buatsi progresses, but with the likes of power puncher Benavidez, and Russian star Dmitry Bivol ruling the division, the path to championship success - judging by this showing - still seems difficult.
Ricky Hatton Homage Fuels All-Manchester Battle
In the secondary fight, Arthur beat Rea by split-decision in a terrific Manchester vs Manchester contest to secure the European light heavyweight championship.
The venue grew hushed for a deeply poignant homage ahead of the contest as 10 bells rang in memory of local hero Ricky Hatton, who passed away at age 46 in September.
It was the initial significant broadcast fight night in the location since Hatton's passing. As the final chime disappeared, the stillness became a roar of "only one Ricky Hatton".
The action during the bout reflected the emotion. The eventual winner was sent to the canvas by a powerful punch directly to the jaw in the early round, standing uncertainly to his footing on the count of eight.
But the Manchester United-red equipment of the fighter soon came forward again. On the opposite side, the opponent - in competitive blue - was damaged soon, noticeable damage forming under his face as the fighters traded powerful shots.
The challenger, twenty-seven, landed power punches but Arthur, thirty-four, responded in kind with effective uppercuts as the pace seldom decreased over twelve rounds.
Arthur barely secured the decision with official scores of even score, 115-113 and clearer margin, but both fighters were relentless and brave, all the qualities their inspiration Hatton embodied.
