UK light-heavyweight Buatsi secured a victory yet disappointing beginning to life under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic medal winner's punch output seemingly secured him a judges' verdict in a close 10-round bout at the boxing arena.
But the challenger had his moments, delivering effective individual punches in a match where the techniques didn't complement each other, with excessive holding disrupting the contest.
The officials scored it 96-94 in favor to the winner, with the final judge a 95-95.
"It wasn't my best showing but what defines champions? They succeed," the victor said in the ringside as he was greeted with boos from the spectators.
The British fighter returned to winning ways after his initial pro loss - an thrilling contest with Callum Smith in last winter - to claim a 20th career victory.
Some ringside observers believed the challenger, thirty-one, should have been awarded the decision but the contender experienced the second setback of his 28-fight professional journey.
Buatsi Claims Triumph in Slow Affair
His career development has plateaued in recent years through management issues and considerable time of lack of fights.
Earlier forecast as the future of the British fight scene, he now is positioned trying to realize his potential - maybe in what feels like a ultimate opportunity - under fresh management.
He opened tentatively, with neither fighter willing to take risks in a cagey initial rounds.
The challenger, whose single earlier setback came at the lower weight class against his former opponent in two years ago after breaking his hand in the contest, was participating in his second bout at light heavyweight.
By the halfway stage, the underdog had stayed in contention, making life awkward for the favorite, who utilized a protective stance to narrowly win the better rounds.
The spectators' acceptance decreased amid regular grabbing, with Parker falling to the floor several times during close exchanges.
The underdog finished the stronger, but multiple periods were difficult to score. Although, former world champion the boxing analyst - providing analysis for the broadcast network - had it strongly leaning for the challenger, awarding Buatsi just a single round.
The victor moves on, but with the presence of hard hitter Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the journey to titles - on this evidence - still looks steep.
Hatton Tribute Motivates Local Rivalry Fight
In the co-main event, Lyndon Arthur beat Rea by divided decision in a outstanding Manchester vs Manchester battle to win the European light-heavyweight title.
The venue grew hushed for a extremely emotional homage ahead of the contest as 10 bells tolled in honor of Manchester's own Hatton, who passed away at age 46 in September.
It was the premier televised fight night in the urban center since Hatton's passing. As the final chime disappeared, the silence became a chant of "only one Hatton".
The competition within the ring reflected the feeling. The eventual winner was sent to the canvas by a powerful punch flush on the chin in the early round, standing uncertainly to his feet on the eight count.
But the red-colored equipment of the fighter soon advanced again. From the other corner, the opponent - in competitive blue - was damaged quickly, noticeable damage forming under his face as the pair exchanged hard punches.
The challenger, 27, delivered effective strikes but the champion, thirty-four, responded in kind with stinging uppercuts as the pace seldom decreased over 12 rounds.
The victor narrowly won the result with judges scorecards of 114-114, 115-113 and clearer margin, but each competitor were persistent and courageous, everything their idol Hatton represented.
