British light heavyweight Buatsi made a winning yet disappointing start to his career under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's work rate likely gained him a judges' verdict in a close ten-round fight at the boxing arena.
But the challenger found success, landing some telling clean blows in a fight where the styles never quite clicked, with constant grabbing marring the fight.
Two judges had it 96-94 to Buatsi, with the final judge a even score.
"It wasn't my finest performance but what do champions do? They prevail," the victor commented in the arena as he was met by boos from the spectators.
The Londoner bounced back after his maiden career setback - an memorable fight with his previous opponent in last winter - to claim a twentieth professional win.
Some ringside observers thought the challenger, thirty-one, should have been awarded the decision but the Derbyshire fighter endured the second defeat of his 28-bout career.
Buatsi Secures Triumph in Slow Affair
His career development has stalled in recent years through contract problems and long spells of inactivity.
Previously predicted as the rising talent of British boxing, he now is positioned trying to realize his potential - possibly in what seems like a ultimate opportunity - under new promotional backing.
He began cautiously, with neither fighter ready to overcommit in a calculated early stages.
The challenger, whose single earlier setback came at the lower weight class against his former opponent in two years ago after breaking his hand during the bout, was making just his second fight at light heavyweight.
By the halfway stage, Parker had stayed in contention, creating difficulties for the favorite, who worked behind a protective stance to barely take the better periods.
The audience's tolerance wore thin amid frequent holding, with the challenger slipping to the canvas various instances during close exchanges.
Parker finished the stronger, but several stanzas were difficult to score. However, previous titleholder Carl Frampton - providing analysis for Dazn - had it strongly leaning for the challenger, awarding Buatsi just only one stanza.
Buatsi progresses, but with the caliber of power puncher Benavidez, and Russian star Dmitry Bivol dominating the weight class, the road to world glory - judging by this showing - still seems difficult.
Ricky Hatton Memorial Fuels All-Manchester Battle
In the co-main event, Arthur overcame Bradley Rea by split-decision in a excellent local rivalry battle to win the European light-heavyweight championship.
The venue became quiet for a profoundly moving homage before the fight as a bell ceremony sounded in memory of the city's native Hatton, who passed away aged 46 in September.
It was the premier televised match card in the urban center since Hatton's passing. As the final chime ended, the quiet transitioned to a roar of "only one Ricky Hatton".
The action within the ring reflected the emotion. Arthur was floored by a powerful punch directly to the face in the second round, standing uncertainly to his position on the referee's count.
But the Manchester United-red shorts of Arthur soon pressed ahead again. On the opposite side, the opponent - in rival City blue - was injured soon, noticeable damage developing under his face as the duo landed powerful shots.
Rea, 27, landed power punches but the champion, 34, matched the intensity with stinging uppercuts as the intensity seldom decreased over 12 rounds.
Arthur barely secured the result with scoring tallies of draw, 115-113 and wider gap, but each competitor were determined and full of heart, exactly what their inspiration the legend stood for.
