British light heavyweight Buatsi secured a victory yet underwhelming debut to life under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's work rate appeared to earn him a majority decision in a close ten-round bout at the Co-op Live Arena.
But the challenger found success, connecting with powerful individual punches in a match where the styles didn't complement each other, with frequent clinching spoiling the contest.
The scoring judges had it 96-94 for to Buatsi, with the third a 95-95.
"It wasn't my greatest display but what do champions do? They succeed," Buatsi said in the arena as he was faced negative reactions from the audience.
The British fighter bounced back after his initial pro loss - an thrilling contest with Callum Smith in February - to claim a 20th pro success.
Some ringside observers believed Parker, thirty-one, merited the decision but the Derbyshire fighter suffered the second loss of his 28-match professional journey.
Buatsi Claims Triumph in Dull Affair
The fighter's advancement has slowed in the past few years through management issues and considerable time of inactivity.
Previously predicted as the future of UK boxing, he now stands trying to realize his potential - maybe in what appears to be a ultimate opportunity - under new promotional backing.
He started carefully, with both competitors willing to overcommit in a cagey initial rounds.
Parker, whose only previous defeat came at super middleweight against John Ryder in two years ago after breaking his hand in the contest, was participating in his second appearance at light heavyweight.
By the halfway stage, the underdog had made it competitive, making life awkward for the favorite, who utilized a tight guard to edge the cleaner rounds.
The spectators' acceptance wore thin because of regular grabbing, with Parker going down several times during close exchanges.
Parker ended stronger, but several stanzas were difficult to score. However, previous titleholder the boxing analyst - working with the broadcast network - had it particularly wide for the challenger, scoring for Buatsi just one round.
The victor advances, but with the presence of hard hitter Benavidez, and Russian champion Dmitry Bivol leading the category, the road to world glory - judging by this showing - still appears challenging.
Ricky Hatton Tribute Inspires Local Rivalry Contest
In the supporting bout, Lyndon Arthur beat Rea by divided decision in a terrific Manchester vs Manchester contest to win the European light-heavyweight belt.
The venue became quiet for a profoundly moving memorial before the fight as a bell ceremony rang in remembrance of Manchester's own Ricky Hatton, who passed away aged 46 in September.
It was the initial significant broadcast match card in the urban center since Hatton's passing. As the final chime faded, the stillness transitioned to a shout of "only one Ricky Hatton".
The action inside the ropes equaled the feeling. Arthur was knocked down by a significant blow directly to the chin in the initial stage, rising shakily to his footing on the referee's count.
But the Manchester United-red attire of the fighter soon came forward again. Across the ring, the opponent - in competitive blue - was damaged soon, significant bruising forming under his eye as the duo traded punishing blows.
Rea, twenty-seven, delivered effective strikes but the champion, thirty-four, responded in kind with effective uppercuts as the intensity rarely dropped over the full distance.
The victor narrowly won the result with scoring tallies of draw, narrow lead and wider gap, but each competitor were relentless and brave, everything their inspiration Hatton represented.
