UK light-heavyweight Buatsi secured a victory yet unimpressive beginning to his career under new promoters with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's activity level seemingly secured him a judges' verdict in a competitive ten-round bout at the boxing arena.
But Parker had his moments, delivering effective single shots in a match where the techniques didn't complement each other, with frequent clinching marring the contest.
The officials scored it 96-94 for to Buatsi, with the final judge a even score.
"It wasn't my best display but how do champions respond? They prevail," the victor commented in the ring as he was greeted with disapproval from the audience.
The Londoner bounced back after his maiden career setback - an thrilling contest with Callum Smith in last winter - to earn a 20th career victory.
Some ringside observers believed Parker, thirty-one, deserved the win but the contender suffered the second defeat of his 28-match career.
The Champion Claims Triumph in Uneventful Match
Buatsi's progress has slowed in recent times through contract problems and long spells of inactivity.
Previously predicted as the rising talent of UK boxing, he now finds himself trying to fulfil that early promise - perhaps in what appears to be a ultimate opportunity - under recent support.
He opened tentatively, with both competitors ready to overcommit in a cagey early stages.
The challenger, whose only previous defeat came at the lower weight class against John Ryder in 2022 after damaging his hand in the contest, was participating in his second fight at light heavyweight.
By the middle rounds, Parker had kept it close, causing problems for the favorite, who worked behind a solid defense to edge the more effective periods.
The audience's tolerance wore thin amid regular grabbing, with Parker slipping to the canvas multiple occasions during close exchanges.
The underdog closed well, but several stanzas were difficult to score. Nevertheless, ex-champion the boxing analyst - providing analysis for the broadcast network - had it significantly in favor for Parker, awarding Buatsi just one round.
Buatsi moves on, but with the presence of heavy hitter Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the road to world glory - judging by this showing - still looks steep.
Ricky Hatton Memorial Inspires All-Manchester Contest
In the supporting bout, Lyndon Arthur beat Bradley Rea by divided decision in a outstanding local rivalry fight to win the continental belt.
The stadium fell silent for a deeply poignant memorial prior to the bout as a bell ceremony sounded in honor of local hero Hatton, who died 46 years old in recently.
It was the initial significant broadcast fight night in the location since the passing of Hatton. As the final chime disappeared, the quiet became a roar of "there's just one Ricky Hatton".
The action inside the ropes reflected the feeling. The eventual winner was sent to the canvas by a powerful punch squarely on the chin in the early round, getting up unsteadily to his footing on the referee's count.
But the red-colored equipment of Arthur soon advanced again. From the other corner, the opponent - in opposing blue - was damaged early, noticeable damage developing under his orbital area as the duo exchanged powerful shots.
Rea, 27, connected with strong blows but the champion, 34, responded in kind with stinging uppercuts as the action hardly diminished over twelve rounds.
Arthur edged the decision with official scores of even score, narrow lead and 115-112, but each competitor were determined and courageous, exactly what their hero Hatton embodied.
