UK light-heavyweight Buatsi secured a victory yet unimpressive start to life under new promoters with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level seemingly secured him a split decision in a close 10-round bout at the boxing arena.
But Parker had his moments, delivering effective single shots in a fight where the styles didn't complement each other, with frequent clinching marring the fight.
The scoring judges judged it 96-94 in favor to the winner, with the remaining official a 95-95.
"It wasn't my finest showing but what do champions do? They succeed," the victor commented in the arena as he was faced boos from the crowd.
The British fighter got back to winning after his maiden career setback - an thrilling contest with his previous opponent in February - to claim a 20th career victory.
Several boxing experts believed Parker, thirty-one, merited the win but the contender experienced the second setback of his 28-fight professional journey.
Buatsi Secures Victory in Uneventful Affair
The fighter's advancement has plateaued in the past few years through promotional disputes and extended periods of lack of fights.
Once tipped as the rising talent of British boxing, he now is positioned trying to fulfil that early promise - possibly in what appears to be a final roll of the dice - under fresh management.
He began cautiously, with both competitors ready to be aggressive in a tentative initial rounds.
Parker, whose only previous defeat 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 fight at light-heavyweight.
By the fight's midpoint, the underdog had kept it close, creating difficulties for Buatsi, who operated with a solid defense to barely take the more effective stanzas.
The spectators' acceptance wore thin because of constant clinching, with the challenger falling to the floor various instances during clinches.
Parker finished the stronger, but many rounds were difficult to score. However, previous titleholder Carl Frampton - working with Dazn - had it strongly leaning for the challenger, awarding Buatsi just only one stanza.
Buatsi progresses, but with the caliber of heavy hitter Benavidez, and Russian star Dmitry Bivol leading the category, the journey to titles - on this evidence - still appears challenging.
Ricky Hatton Tribute Inspires Local Rivalry Contest
In the secondary fight, Arthur defeated Rea by split-decision in a terrific Manchester vs Manchester fight to secure the European light-heavyweight championship.
The arena fell silent for a deeply poignant tribute before the fight as a bell ceremony sounded in remembrance of local hero Hatton, who passed away at age 46 in last month.
It was the first major televised match card in the location since the passing of Hatton. As the concluding sound faded, the quiet transitioned to a shout of "only one Hatton".
The action within the ring equaled the emotion. The eventual winner was sent to the canvas by a powerful punch directly to the chin in the early round, rising shakily to his footing on the referee's count.
But the traditional red equipment of Arthur soon advanced again. Across the ring, the opponent - in rival City blue - was damaged quickly, noticeable damage forming under his orbital area as the duo exchanged hard punches.
Rea, twenty-seven, delivered effective strikes but the champion, thirty-four, fought fire with fire with effective uppercuts as the action hardly diminished over the full distance.
The victor edged the result with judges scorecards of even score, narrow lead and clearer margin, but each competitor were determined and courageous, exactly what their inspiration the legend represented.
