British light heavyweight Buatsi earned a win yet disappointing start to life under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level appeared to earn him a majority decision in a close 10-round contest at the Co-op Live Arena.
But Parker had his moments, landing some telling single shots in a fight where the approaches failed to mesh, with constant grabbing marring the fight.
The officials had it 96-94 in favor to the winner, with the third a even score.
"It wasn't my greatest showing but how do champions respond? They prevail," Buatsi commented in the ring as he was met by disapproval from the crowd.
The British fighter got back to winning after his initial pro loss - an memorable fight with Callum Smith in last winter - to claim a 20th pro success.
Several boxing experts felt the challenger, thirty-one, should have been awarded the victory but the Derbyshire fighter experienced the second setback of his 28-match career.
The Champion Earns Victory in Dull Match
His career development has plateaued in recent times through promotional disputes and long spells of inactivity.
Once tipped as the rising talent of British boxing, he now is positioned trying to fulfil that early promise - possibly in what seems like a final roll of the dice - under recent support.
He opened tentatively, with both competitors willing to be aggressive in a tentative early stages.
Parker, whose only previous defeat came at the lower weight class against John Ryder in 2022 after suffering a hand injury during the bout, was making just his second fight at light-heavyweight.
By the middle rounds, the underdog had stayed in contention, making life awkward for Buatsi, who operated with a tight guard to narrowly win the cleaner stanzas.
The crowd's patience wore thin amid regular grabbing, with the challenger falling to the floor several times during clinches.
The underdog closed well, but many rounds were hard to judge. Although, previous titleholder the boxing analyst - providing analysis for Dazn - had it particularly wide for Parker, scoring for Buatsi just one round.
The victor moves on, but with the likes of heavy hitter Benavidez, and Russian star Dmitry Bivol ruling the division, the journey to titles - based on this performance - still appears challenging.
Hatton Homage Inspires Manchester Derby Battle
In the secondary fight, Arthur beat Bradley Rea by close verdict in a outstanding local rivalry battle to secure the European light heavyweight title.
The arena became quiet for a deeply poignant tribute before the fight as ten bells tolled in memory of the city's native Hatton, who died aged 46 in last month.
It was the premier televised fight night in the location since the passing of Hatton. As the final chime faded, the stillness became a roar of "there's only one Hatton".
The action during the bout matched the emotion. The eventual winner was knocked down by a left hook directly to the face in the second round, rising shakily to his feet on the eight count.
But the red-colored shorts of the fighter soon pressed ahead again. On the opposite side, the opponent - in competitive blue - was damaged early, heavy swelling appearing under his orbital area as the duo traded punishing blows.
Rea, 27, connected with strong blows but Arthur, 34, matched the intensity with effective uppercuts as the action rarely dropped over the full distance.
Arthur barely secured the result with official scores of even score, close margin and 115-112, but each competitor were relentless and courageous, all the qualities their hero the legend represented.
