British light-heavyweight Buatsi made a winning yet underwhelming debut to his career under fresh promotional backing with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate likely gained him a judges' verdict in a competitive 10-round bout at the Co-op Live Arena.
But the challenger had his moments, landing some telling single shots in a fight where the techniques never quite clicked, with excessive holding marring the contest.
The officials had it 96-94 to the winner, with the third a 95-95 draw.
"It wasn't my finest display but what defines champions? They prevail," the victor stated in the ring as he was met by boos from the audience.
The British fighter got back to winning after his maiden career setback - an thrilling contest with Callum Smith in February - to claim a twentieth professional win.
Some ringside observers felt Parker, thirty-one, deserved the victory but the British boxer experienced the second loss of his 28-bout career.
The Champion Earns Victory in Dull Affair
His career development has stalled in the past few years through promotional disputes and long spells of inactivity.
Once tipped as the future of the British fight scene, he now is positioned trying to fulfil that early promise - perhaps in what appears to be a last chance - under new promotional backing.
He started carefully, with the two boxers ready to overcommit in a cagey opening few rounds.
The challenger, whose only previous defeat came at the lower weight class against his former opponent in 2022 after suffering a hand injury during the bout, was participating in his second appearance at the higher weight class.
By the fight's midpoint, the underdog had stayed in contention, causing problems for the favorite, who utilized a solid defense to narrowly win the cleaner rounds.
The spectators' acceptance decreased amid frequent holding, with Parker slipping to the canvas various instances during clinches.
The underdog finished the stronger, but several stanzas were hard to judge. Although, former world champion the boxing analyst - providing analysis for Dazn - had it strongly leaning for Parker, scoring for Buatsi just only one stanza.
Buatsi progresses, but with the presence of power puncher Benavidez, and Russian star Dmitry Bivol dominating the weight class, the road to world glory - based on this performance - still looks steep.
Hatton Homage Fuels All-Manchester Contest
In the supporting bout, Arthur beat Rea by divided decision in a terrific local rivalry fight to secure the European light-heavyweight championship.
The stadium grew hushed for a profoundly moving tribute ahead of the contest as a bell ceremony rang in memory of Manchester's own Hatton, who passed away at age 46 in last month.
It was the initial significant broadcast boxing event in the location since the passing of Hatton. As the concluding sound disappeared, the silence transitioned to a roar of "there's just one Ricky Hatton".
The fighting within the ring equaled the emotion. The eventual winner was floored by a left hook flush on the jaw in the early round, standing uncertainly to his position on the referee's count.
But the red-colored shorts of Arthur soon pressed ahead again. From the other corner, Rea - in rival City blue - was marked up quickly, significant bruising developing under his orbital area as the duo landed hard punches.
Rea, 27, landed power punches but the champion, thirty-four, matched the intensity with effective uppercuts as the action rarely dropped over twelve rounds.
The victor edged the result with scoring tallies of draw, narrow lead and 115-112, but both fighters were determined and full of heart, all the qualities their idol Hatton embodied.
