British light heavyweight Buatsi earned a win yet disappointing beginning to life under fresh promotional backing with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level appeared to earn him a majority decision in a tight ten-round fight at the boxing arena.
But Parker landed significant shots, connecting with powerful clean blows in a match where the techniques never quite clicked, with excessive holding spoiling the contest.
Two judges judged it 96-94 to the winner, with the remaining official a 95-95.
"It wasn't my greatest showing but what defines champions? They win," the victor commented in the arena as he was greeted with negative reactions from the audience.
The Londoner got back to winning after his maiden career setback - an epic battle with his previous opponent in last winter - to claim a twentieth professional win.
Various analysts believed the challenger, 31, merited the decision but the contender experienced the second loss of his 28-bout career.
Buatsi Secures Win in Uneventful Affair
The fighter's advancement has stalled in recent years through promotional disputes and extended periods of lack of fights.
Earlier forecast as the future of British boxing, he now stands trying to realize his potential - maybe in what seems like a final roll of the dice - under fresh management.
He opened tentatively, with neither fighter ready to be aggressive in a cagey opening few rounds.
Parker, whose single earlier setback came at super-middleweight against John Ryder in two years ago after damaging his hand mid-fight, was making just his second fight at light heavyweight.
By the halfway stage, the underdog had stayed in contention, creating difficulties for Buatsi, who utilized a solid defense to edge the more effective periods.
The audience's tolerance diminished during regular grabbing, with Parker slipping to the canvas several times during grappling.
Parker finished the stronger, but multiple periods were challenging to assess. However, previous titleholder the boxing analyst - working with the broadcast network - had it strongly leaning for Parker, awarding Buatsi just a single round.
Buatsi advances, but with the likes of hard hitter Benavidez, and Russian champion Dmitry Bivol ruling the division, the journey to titles - judging by this showing - still appears challenging.
Ricky Hatton Memorial Fuels Local Rivalry Fight
In the secondary fight, Arthur defeated Bradley Rea by divided decision in a terrific all-Manchester contest to capture the European light heavyweight title.
The stadium became quiet for a deeply poignant memorial before the fight as 10 bells tolled in memory of local hero Ricky Hatton, who passed away at age 46 in last month.
It was the first major televised boxing event in the city since the passing of Hatton. As the concluding sound disappeared, the stillness gave way to a roar of "there's just one Hatton".
The fighting within the ring reflected the feeling. The eventual winner was floored by a significant blow flush on the face in the initial stage, rising shakily to his footing on the referee's count.
But the Manchester United-red shorts of Arthur soon advanced again. From the other corner, the opponent - in opposing blue - was damaged quickly, heavy swelling forming under his orbital area as the pair landed powerful shots.
The challenger, twenty-seven, delivered effective strikes but the champion, 34, fought fire with fire with stinging uppercuts as the action hardly diminished over the full distance.
The victor edged the decision with judges scorecards of draw, narrow lead and clearer margin, but both fighters were relentless and full of heart, all the qualities their hero Hatton embodied.
