British light heavyweight Buatsi earned a win yet unimpressive start to life under fresh promotional backing with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's punch output appeared to earn him a split decision in a tight ten-round fight at the Co-op Live Arena.
But the challenger found success, landing some telling single shots in a contest where the styles never quite clicked, with constant grabbing spoiling the fight.
The scoring judges scored it 96-94 to the winner, with the remaining official a 95-95.
"It wasn't my greatest performance but what defines champions? They win," Buatsi said in the ringside as he was met by negative reactions from the spectators.
The Londoner returned to winning ways after his initial pro loss - an memorable fight with Callum Smith in February - to claim a twentieth professional win.
Several boxing experts felt Parker, 31, deserved the win but the Derbyshire fighter suffered the second defeat of his 28-bout professional journey.
The Champion Secures Victory in Dull Match
Buatsi's progress has slowed in the past few years through management issues and considerable time of inactivity.
Once tipped as the future of the British fight scene, he now finds himself trying to fulfil that early promise - possibly in what seems like a last chance - under new promotional backing.
He began cautiously, with the two boxers willing to overcommit in a cagey opening few rounds.
Parker, whose single earlier setback came at super-middleweight against John Ryder in 2022 after suffering a hand injury during the bout, was participating in his second bout at light heavyweight.
By the fight's midpoint, Parker had stayed in contention, creating difficulties for the favorite, who operated with a tight guard to edge the better periods.
The spectators' acceptance diminished during constant clinching, with the challenger going down various instances during grappling.
Parker closed well, but multiple periods were hard to judge. Nevertheless, former world champion the boxing analyst - commentating on the broadcast network - had it significantly in favor for the challenger, giving Buatsi just only one stanza.
Buatsi advances, but with the caliber of hard hitter Benavidez, and Russian star Bivol ruling the division, the journey to titles - based on this performance - still seems difficult.
Hatton Homage Fuels All-Manchester Battle
In the secondary fight, Arthur defeated Bradley Rea by close verdict in a terrific local rivalry battle to capture the continental title.
The venue became quiet for a deeply poignant memorial prior to the bout as 10 bells sounded in honor of Manchester's own Ricky Hatton, who passed away at age 46 in September.
It was the premier televised boxing event in the urban center since Hatton's death. As the final chime ended, the stillness transitioned to a chant of "only one Hatton".
The fighting during the bout reflected the feeling. The eventual winner was sent to the canvas by a powerful punch directly to the chin in the second round, getting up unsteadily to his feet on the referee's count.
But the red-colored equipment of Arthur soon pressed ahead again. From the other corner, Rea - in rival City blue - was marked up quickly, significant bruising developing under his face as the pair landed punishing blows.
The challenger, twenty-seven, connected with strong blows but Arthur, thirty-four, matched the intensity with stinging uppercuts as the pace hardly diminished over 12 rounds.
Arthur edged the result with official scores of draw, 115-113 and wider gap, but each competitor were determined and courageous, exactly what their hero the legend embodied.
