UK light-heavyweight Buatsi secured a victory yet disappointing beginning to his career under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic medal winner's work rate likely gained him a split decision in a tight ten-round contest at the Manchester venue.
But Parker found success, connecting with powerful single shots in a fight where the styles didn't complement each other, with constant grabbing disrupting the fight.
The scoring judges judged it 96-94 in favor to Buatsi, with the third a 95-95 draw.
"It wasn't my greatest display but what do champions do? They prevail," Buatsi stated in the ringside as he was greeted with boos from the audience.
The British fighter returned to winning ways after his first professional defeat - an thrilling contest with his previous opponent in February - to secure a twentieth professional win.
Several boxing experts felt Parker, 31, deserved the decision but the British boxer suffered the second loss of his 28-fight professional journey.
Buatsi Secures Win in Dull Encounter
Buatsi's progress has plateaued in recent times through contract problems and long spells of lack of fights.
Previously predicted as the next star of British boxing, he now is positioned trying to realize his potential - maybe in what appears to be a final roll of the dice - under recent support.
He opened tentatively, with neither fighter willing to overcommit in a tentative initial rounds.
The challenger, whose single earlier setback came at super middleweight against his former opponent in 2022 after breaking his hand during the bout, was competing in only his second fight at the higher weight class.
By the fight's midpoint, the underdog had kept it close, making life awkward for Buatsi, who operated with a tight guard to edge the more effective stanzas.
The spectators' acceptance diminished during regular grabbing, with Parker going down multiple occasions during close exchanges.
Parker ended stronger, but multiple periods were challenging to assess. Although, previous titleholder the boxing analyst - providing analysis for the broadcast network - had it particularly wide for the challenger, giving Buatsi just one round.
Buatsi advances, but with the caliber of power puncher Benavidez, and Russian champion Bivol dominating the weight class, the path to championship success - based on this performance - still appears challenging.
Ricky Hatton Tribute Fuels All-Manchester Battle
In the secondary fight, Arthur defeated Bradley Rea by split-decision in a terrific Manchester vs Manchester battle to capture the European light heavyweight belt.
The arena fell silent for a extremely emotional memorial ahead of the contest as ten bells rang in memory of Manchester's own Ricky Hatton, who died 46 years old in last month.
It was the initial significant broadcast match card in the urban center since Hatton's passing. As the final chime ended, the silence became a shout of "there's just one Hatton".
The competition within the ring equaled the feeling. Arthur was knocked down by a significant blow directly to the chin in the second round, standing uncertainly to his footing on the count of eight.
But the traditional red attire of Arthur soon came forward again. Across the ring, the opponent - in rival City blue - was damaged quickly, significant bruising appearing under his orbital area as the fighters exchanged punishing blows.
The challenger, twenty-seven, landed power punches but the champion, 34, fought fire with fire with effective uppercuts as the action rarely dropped over 12 rounds.
Arthur barely secured the decision with scoring tallies of 114-114, close margin and wider gap, but the two athletes were relentless and courageous, all the qualities their inspiration the legend stood for.
