UK light heavyweight Buatsi earned a win yet unimpressive start to life under fresh promotional backing with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level likely gained him a majority decision in a competitive ten-round bout at the boxing arena.
But the challenger had his moments, connecting with powerful single shots in a contest where the styles failed to mesh, with frequent clinching spoiling the fight.
The officials judged it 96-94 in favor to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my greatest performance but how do champions respond? They prevail," the victor said in the ring as he was met by disapproval from the spectators.
The Londoner bounced back after his initial pro loss - an epic battle with Callum Smith in last winter - to secure a 20th career victory.
Several boxing experts thought Parker, 31, deserved the victory but the British boxer endured the second loss of his 28-match career.
The Champion Claims Win in Dull Encounter
His career development has stalled in recent times through contract problems and long spells of lack of fights.
Earlier forecast as the next star of the British fight scene, he now stands trying to fulfil that early promise - perhaps in what seems like a ultimate opportunity - under new promotional backing.
He opened tentatively, with both competitors willing to take risks in a tentative initial rounds.
The challenger, whose only previous defeat came at super middleweight against John Ryder in two years ago after breaking his hand during the bout, was participating in his second fight at light-heavyweight.
By the middle rounds, the underdog had stayed in contention, creating difficulties for Buatsi, who utilized a protective stance to edge the more effective stanzas.
The spectators' acceptance wore thin amid regular grabbing, with Parker slipping to the canvas multiple occasions during close exchanges.
The underdog finished the stronger, but several stanzas were difficult to score. However, ex-champion Carl Frampton - providing analysis for Dazn - had it strongly leaning for Parker, giving Buatsi just one round.
Buatsi progresses, but with the caliber of heavy hitter Benavidez, and Russian champion Dmitry Bivol ruling the division, the road to world glory - on this evidence - still seems difficult.
Hatton Memorial Motivates All-Manchester Battle
In the secondary fight, Arthur overcame Rea by close verdict in a outstanding Manchester vs Manchester battle to win the European light-heavyweight title.
The venue fell silent for a profoundly moving tribute ahead of the contest as a bell ceremony rang in honor of local hero Hatton, who passed away 46 years old in last month.
It was the initial significant broadcast boxing event in the city since the passing of Hatton. As the last bell disappeared, the silence gave way to a roar of "only one Hatton".
The action during the bout matched the feeling. The eventual winner was sent to the canvas by a powerful punch squarely on the face in the initial stage, getting up unsteadily to his feet on the referee's count.
But the traditional red shorts of Arthur soon came forward again. Across the ring, Rea - in competitive blue - was marked up soon, significant bruising developing under his eye as the fighters landed powerful shots.
The challenger, twenty-seven, connected with strong blows but Arthur, thirty-four, matched the intensity with powerful upward punches as the action hardly diminished over 12 rounds.
The victor barely secured the verdict with official scores of 114-114, narrow lead and wider gap, but each competitor were relentless and courageous, everything their inspiration Hatton stood for.
