British light heavyweight Buatsi earned a win yet disappointing start to life under fresh promotional backing with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level likely gained him a split decision in a close ten-round fight at the Co-op Live Arena.
But Parker had his moments, delivering effective individual punches in a contest where the techniques didn't complement each other, with constant grabbing marring the contest.
The scoring judges judged it 96-94 to Buatsi, with the third a 95-95.
"It wasn't my finest display but how do champions respond? They succeed," the victor commented in the ringside as he was greeted with disapproval from the audience.
The Londoner bounced back after his initial pro loss - an epic battle with his previous opponent in last winter - to claim a 20th career victory.
Several boxing experts felt Parker, thirty-one, should have been awarded the victory but the contender experienced the second loss of his 28-fight professional journey.
Buatsi Earns Victory in Slow Affair
Buatsi's progress has plateaued in recent times through promotional disputes and long spells of lack of fights.
Earlier forecast as the rising talent of British boxing, he now finds himself trying to fulfil that early promise - possibly in what appears to be a last chance - under fresh management.
He started carefully, with neither fighter willing to take risks in a cagey opening few rounds.
Parker, whose single earlier setback came at super middleweight against his former opponent in 2022 after breaking his hand mid-fight, was participating in his second bout at light-heavyweight.
By the middle rounds, the underdog had stayed in contention, causing problems for Buatsi, who utilized a tight guard to edge the cleaner periods.
The spectators' acceptance decreased because of constant clinching, with the challenger falling to the floor various instances during clinches.
The underdog finished the stronger, but several stanzas were challenging to assess. Although, previous titleholder the boxing analyst - commentating on Dazn - had it significantly in favor for the challenger, scoring for Buatsi just one round.
Buatsi moves on, but with the presence of power puncher Benavidez, and Russian champion Bivol ruling the division, the road to world glory - judging by this showing - still looks steep.
Ricky Hatton Memorial Inspires Local Rivalry Battle
In the secondary fight, Arthur beat Rea by divided decision in a outstanding Manchester vs Manchester fight to secure the European light heavyweight championship.
The stadium fell silent for a deeply poignant memorial prior to the bout as 10 bells sounded in honor of local hero Ricky Hatton, who died aged 46 in recently.
It was the premier televised match card in the location since Hatton's passing. As the final chime disappeared, the stillness gave way to a shout of "there's only one Hatton".
The action during the bout equaled the feeling. The eventual winner was floored by a powerful punch squarely on the face in the initial stage, standing uncertainly to his footing on the referee's count.
But the Manchester United-red shorts of the fighter soon pressed ahead again. Across the ring, the opponent - in rival City blue - was injured soon, heavy swelling appearing under his face as the duo landed powerful shots.
The challenger, 27, connected with strong blows but Arthur, 34, fought fire with fire with effective uppercuts as the action hardly diminished over the full distance.
The victor barely secured the result with official scores of 114-114, 115-113 and 115-112, but both fighters were determined and brave, everything their hero Hatton represented.
