UK light heavyweight Buatsi secured a victory yet unimpressive debut to life under fresh promotional backing with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate seemingly secured him a majority decision in a close 10-round contest at the boxing arena.
But the challenger had his moments, delivering effective individual punches in a contest where the approaches failed to mesh, with excessive holding marring the action.
The officials had it 96-94 for to the winner, with the remaining official a 95-95.
"It wasn't my greatest showing but what do champions do? They prevail," Buatsi said in the ringside as he was faced disapproval from the spectators.
The British fighter returned to winning ways after his first professional defeat - an thrilling contest with his previous opponent in February - to secure a 20th pro success.
Various analysts thought the challenger, thirty-one, should have been awarded the decision but the British boxer experienced the second defeat of his 28-bout professional journey.
The Champion Earns Victory in Slow Match
His career development has plateaued in recent times through contract problems and extended periods of inactivity.
Earlier forecast as the future of the British fight scene, he now finds himself trying to fulfil that early promise - perhaps in what appears to be a last chance - under fresh management.
He started carefully, with both competitors prepared to be aggressive in a calculated opening few rounds.
Parker, whose sole prior loss came at super middleweight against his former opponent in two years ago after suffering a hand injury during the bout, was competing in only his second bout at light-heavyweight.
By the middle rounds, the underdog had made it competitive, causing problems for the favorite, who utilized a tight guard to edge the more effective rounds.
The audience's tolerance diminished amid constant clinching, with the challenger going down various instances during close exchanges.
The underdog ended stronger, but multiple periods were difficult to score. However, ex-champion the boxing analyst - commentating on the broadcast network - had it significantly in favor for Parker, awarding Buatsi just one round.
The victor advances, but with the presence of hard hitter Benavidez, and Russian star Dmitry Bivol ruling the division, the journey to titles - judging by this showing - still looks steep.
Ricky Hatton Homage Inspires Manchester Derby Battle
In the supporting bout, Lyndon Arthur defeated Bradley Rea by close verdict in a excellent local rivalry contest to win the European light heavyweight belt.
The venue became quiet for a extremely emotional homage ahead of the contest as ten bells tolled in remembrance of the city's native Ricky Hatton, who succumbed at age 46 in last month.
It was the initial significant broadcast fight night in the urban center since Hatton's death. As the concluding sound disappeared, the stillness gave way to a roar of "there's just one Hatton".
The competition inside the ropes matched the emotion. The eventual winner was sent to the canvas by a significant blow squarely on the face in the early round, standing uncertainly to his position on the referee's count.
But the traditional red equipment of Arthur soon advanced again. On the opposite side, Rea - in opposing blue - was damaged quickly, heavy swelling appearing under his orbital area as the pair exchanged hard punches.
The challenger, twenty-seven, landed power punches but Arthur, thirty-four, matched the intensity with effective uppercuts as the action hardly diminished over 12 rounds.
Arthur barely secured the result with scoring tallies of even score, narrow lead and 115-112, but both fighters were relentless and full of heart, all the qualities their idol the legend embodied.
