UK light heavyweight Buatsi secured a victory yet disappointing beginning to his career under fresh promotional backing with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level appeared to earn him a majority decision in a competitive 10-round bout at the boxing arena.
But the challenger found success, connecting with powerful single shots in a contest where the styles failed to mesh, with frequent clinching disrupting the action.
The officials scored it 96-94 in favor to the winner, with the remaining official a 95-95.
"It wasn't my greatest display but how do champions respond? They prevail," Buatsi commented in the ring as he was faced boos from the crowd.
The British fighter got back to winning after his first professional defeat - an epic battle with his previous opponent in last winter - to earn a 20th pro success.
Various analysts felt Parker, 31, merited the victory but the Derbyshire fighter suffered the second defeat of his 28-fight career.
The Champion Secures Triumph in Dull Encounter
The fighter's advancement has stalled in recent years through management issues and long spells of inactivity.
Previously predicted as the future of British boxing, he now stands trying to realize his potential - possibly in what seems like a last chance - under recent support.
He started carefully, with neither fighter ready to be aggressive in a cagey initial rounds.
Parker, whose single earlier setback came at super-middleweight against John Ryder in two years ago after suffering a hand injury mid-fight, was making just his second fight at the higher weight class.
By the halfway stage, the underdog had stayed in contention, making life awkward for Buatsi, who operated with a protective stance to edge the more effective stanzas.
The spectators' acceptance wore thin during regular grabbing, with Parker slipping to the canvas several times during clinches.
Parker closed well, but multiple periods were hard to judge. However, previous titleholder the boxing analyst - providing analysis for the broadcast network - had it strongly leaning for the challenger, giving Buatsi just one round.
The victor moves on, but with the presence of power puncher Benavidez, and Russian star Bivol ruling the division, the journey to titles - judging by this showing - still appears challenging.
Ricky Hatton Homage Motivates All-Manchester Contest
In the co-main event, Arthur beat Bradley Rea by split-decision in a outstanding Manchester vs Manchester contest to win the European light-heavyweight belt.
The stadium grew hushed for a profoundly moving homage prior to the bout as a bell ceremony sounded in honor of Manchester's own Hatton, who died 46 years old in recently.
It was the premier televised match card in the city since the passing of Hatton. As the final chime faded, the quiet gave way to a chant of "there's just one Ricky Hatton".
The action within the ring matched the sentiment. The eventual winner was floored by a significant blow flush on the face in the initial stage, getting up unsteadily to his position on the eight count.
But the traditional red attire of Arthur soon advanced again. From the other corner, the opponent - in competitive blue - was marked up soon, noticeable damage forming under his face as the duo traded powerful shots.
The challenger, twenty-seven, landed power punches but the champion, thirty-four, fought fire with fire with powerful upward punches as the pace seldom decreased over the full distance.
Arthur narrowly won the decision with scoring tallies of 114-114, 115-113 and wider gap, but the two athletes were persistent and full of heart, everything their idol Hatton embodied.
