UK light-heavyweight Buatsi earned a win yet unimpressive start to life under fresh promotional backing with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level seemingly secured him a majority decision in a competitive 10-round contest at the Co-op Live Arena.
But Parker had his moments, connecting with powerful single shots in a match where the techniques failed to mesh, with constant grabbing marring the contest.
The scoring judges had it 96-94 in favor to Buatsi, with the final judge a 95-95.
"It wasn't my greatest display but what defines champions? They succeed," the victor commented in the ring as he was greeted with disapproval from the audience.
The British fighter returned to winning ways after his maiden career setback - an epic battle with his previous opponent in February - to secure a 20th career victory.
Various analysts believed the challenger, thirty-one, should have been awarded the decision but the Derbyshire fighter suffered the second defeat of his 28-match professional journey.
The Champion Claims Victory in Slow Affair
Buatsi's progress has slowed in the past few years through promotional disputes and extended periods of lack of fights.
Earlier forecast as the next star of UK boxing, he now is positioned trying to realize his potential - perhaps in what seems like a final roll of the dice - under fresh management.
He began cautiously, with the two boxers ready to take risks in a tentative early stages.
Parker, whose sole prior loss came at super middleweight against his former opponent in two years ago after breaking his hand in the contest, was competing in only his second fight at the higher weight class.
By the halfway stage, the underdog had made it competitive, making life awkward for the favorite, who operated with a solid defense to edge the better rounds.
The spectators' acceptance decreased amid regular grabbing, with the challenger going down various instances during close exchanges.
The underdog ended stronger, but many rounds were challenging to assess. Nevertheless, ex-champion the boxing analyst - providing analysis for the broadcast network - had it strongly leaning for Parker, giving Buatsi just one round.
The victor moves on, but with the presence of heavy hitter Benavidez, and Russian star Bivol dominating the weight class, the path to championship success - judging by this showing - still seems difficult.
Hatton Memorial Inspires Local Rivalry Fight
In the supporting bout, Lyndon Arthur overcame Rea by split-decision in a terrific Manchester vs Manchester fight to win the continental championship.
The venue grew hushed for a extremely emotional tribute prior to the bout as ten bells sounded in remembrance of local hero Ricky Hatton, who succumbed aged 46 in last month.
It was the initial significant broadcast match card in the location since Hatton's death. As the concluding sound disappeared, the silence gave way to a chant of "only one Ricky Hatton".
The competition during the bout matched the sentiment. The eventual winner was knocked down by a significant blow directly to the chin in the second round, standing uncertainly to his footing on the eight count.
But the red-colored equipment of Arthur soon advanced again. On the opposite side, the opponent - in opposing blue - was damaged early, noticeable damage forming under his face as the fighters landed powerful shots.
The challenger, twenty-seven, landed power punches but the champion, 34, fought fire with fire with effective uppercuts as the pace seldom decreased over the full distance.
The victor narrowly won the result with judges scorecards of even score, close margin and clearer margin, but each competitor were determined and full of heart, all the qualities their inspiration Hatton represented.
