UK light-heavyweight Buatsi secured a victory yet underwhelming debut to life under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's work rate seemingly secured him a majority decision in a competitive 10-round contest at the Manchester venue.
But Parker landed significant shots, delivering effective clean blows in a fight where the approaches never quite clicked, with frequent clinching spoiling the fight.
The scoring judges had it 96-94 for to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my greatest showing but how do champions respond? They succeed," the victor commented in the ring as he was greeted with disapproval from the spectators.
The Londoner returned to winning ways after his first professional defeat - an memorable fight with Callum Smith in February - to earn a 20th pro success.
Some ringside observers felt the challenger, 31, should have been awarded the victory but the contender endured the second setback of his 28-bout career.
Buatsi Claims Victory in Dull Affair
Buatsi's progress has stalled in recent years through management issues and long spells of lack of fights.
Previously predicted as the rising talent of the British fight scene, he now is positioned trying to achieve expectations - possibly in what appears to be a last chance - under recent support.
He began cautiously, with the two boxers ready to overcommit in a tentative early stages.
Parker, whose only previous defeat came at super-middleweight against his former opponent in two years ago after suffering a hand injury mid-fight, was competing in only his second bout at the higher weight class.
By the halfway stage, Parker had made it competitive, making life awkward for the favorite, who operated with a protective stance to narrowly win the more effective rounds.
The audience's tolerance diminished because of constant clinching, with the challenger slipping to the canvas multiple occasions during close exchanges.
The underdog closed well, but several stanzas were challenging to assess. Although, ex-champion the boxing analyst - working with Dazn - had it significantly in favor for Parker, giving Buatsi just a single round.
The victor progresses, but with the caliber of heavy hitter Benavidez, and Russian champion Dmitry Bivol leading the category, the path to championship success - judging by this showing - still looks steep.
Ricky Hatton Memorial Inspires Local Rivalry Battle
In the secondary fight, Arthur overcame Bradley Rea by split-decision in a terrific Manchester vs Manchester contest to win the European light heavyweight title.
The venue became quiet for a extremely emotional memorial before the fight as ten bells sounded in memory of Manchester's own Hatton, who died aged 46 in last month.
It was the premier televised fight night in the city since the passing of Hatton. As the concluding sound faded, the silence gave way to a roar of "there's just one Hatton".
The fighting inside the ropes equaled the feeling. Arthur was floored by a powerful punch directly to the face in the second round, rising shakily to his feet on the count of eight.
But the Manchester United-red equipment of Arthur soon pressed ahead again. From the other corner, Rea - in rival City blue - was damaged early, noticeable damage developing under his eye as the duo traded hard punches.
Rea, twenty-seven, connected with strong blows but Arthur, thirty-four, fought fire with fire with stinging uppercuts as the intensity rarely dropped over 12 rounds.
The victor edged the verdict with official scores of 114-114, narrow lead and 115-112, but each competitor were relentless and courageous, exactly what their hero Hatton embodied.
