UK light-heavyweight Buatsi made a winning yet disappointing beginning to life under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic medal winner's work rate seemingly secured him a split decision in a tight 10-round contest at the boxing arena.
But the challenger landed significant shots, delivering effective individual punches in a fight where the techniques failed to mesh, with excessive holding disrupting the contest.
The officials had it 96-94 to the winner, with the final judge a 95-95 draw.
"It wasn't my best performance but how do champions respond? They win," Buatsi said in the ring as he was met by disapproval from the spectators.
The British fighter returned to winning ways after his first professional defeat - an memorable fight with Callum Smith in February - to claim a twentieth professional win.
Some ringside observers felt Parker, 31, merited the victory but the Derbyshire fighter endured the second loss of his 28-fight career.
Buatsi Earns Triumph in Slow Match
His career development has plateaued in recent years through promotional disputes and extended periods of lack of fights.
Earlier forecast as the rising talent of British boxing, he now stands trying to achieve expectations - perhaps in what seems like a final roll of the dice - under recent support.
He began cautiously, with the two boxers ready to be aggressive in a cagey early stages.
Parker, whose single earlier setback came at the lower weight class against John Ryder in 2022 after damaging his hand in the contest, was competing in only his second bout at the higher weight class.
By the middle rounds, the underdog had kept it close, making life awkward for Buatsi, who utilized a solid defense to barely take the better stanzas.
The spectators' acceptance diminished because of regular grabbing, with the challenger going down multiple occasions during grappling.
The underdog finished the stronger, but several stanzas were difficult to score. Nevertheless, previous titleholder Carl Frampton - commentating on Dazn - had it strongly leaning for the challenger, scoring for Buatsi just only one stanza.
The victor moves on, but with the likes of hard hitter Benavidez, and Eastern European fighter Bivol dominating the weight class, the journey to titles - based on this performance - still looks steep.
Ricky Hatton Memorial Inspires All-Manchester Fight
In the supporting bout, Arthur defeated Bradley Rea by close verdict in a outstanding Manchester vs Manchester contest to capture the European light heavyweight belt.
The venue became quiet for a profoundly moving memorial ahead of the contest as ten bells tolled in memory of local hero Ricky Hatton, who passed away at age 46 in last month.
It was the initial significant broadcast boxing event in the city since Hatton's death. As the final chime faded, the silence became a chant of "only one Hatton".
The competition within the ring reflected the sentiment. Arthur was knocked down by a significant blow directly to the chin in the second round, rising shakily to his footing on the referee's count.
But the traditional red attire of the fighter soon came forward again. On the opposite side, the opponent - in opposing blue - was injured soon, heavy swelling forming under his orbital area as the duo landed punishing blows.
The challenger, twenty-seven, landed power punches but the champion, thirty-four, fought fire with fire with effective uppercuts as the action seldom decreased over twelve rounds.
Arthur barely secured the decision with scoring tallies of draw, 115-113 and wider gap, but each competitor were determined and brave, everything their idol the legend stood for.
