UK light-heavyweight Buatsi secured a victory yet unimpressive beginning to his career under fresh promotional backing with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate appeared to earn him a judges' verdict in a tight ten-round bout at the Manchester venue.
But the challenger had his moments, landing some telling individual punches in a contest where the approaches never quite clicked, with frequent clinching marring the action.
The scoring judges had it 96-94 to the winner, with the third a 95-95.
"It wasn't my finest showing but how do champions respond? They win," Buatsi stated in the ring as he was met by negative reactions from the audience.
The British fighter returned to winning ways after his first professional defeat - an thrilling contest with Callum Smith in last winter - to earn a 20th career victory.
Several boxing experts thought Parker, 31, deserved the victory but the British boxer experienced the second loss of his 28-match career.
The Champion Secures Triumph in Uneventful Match
His career development has stalled in recent times through management issues and long spells of lack of fights.
Earlier forecast as the rising talent of the British fight scene, he now finds himself trying to fulfil that early promise - possibly in what feels like a ultimate opportunity - under fresh management.
He started carefully, with both competitors willing to take risks in a cagey early stages.
The challenger, whose sole prior loss came at the lower weight class against John Ryder in 2022 after suffering a hand injury in the contest, was participating in his second appearance at the higher weight class.
By the middle rounds, the underdog had made it competitive, creating difficulties for Buatsi, who operated with a solid defense to barely take the more effective periods.
The audience's tolerance diminished during frequent holding, with the challenger falling to the floor various instances during clinches.
The underdog closed well, but multiple periods were challenging to assess. However, former world champion the boxing analyst - commentating on Dazn - had it particularly wide for the challenger, giving Buatsi just one round.
Buatsi advances, but with the presence of hard hitter Benavidez, and Russian star Bivol ruling the division, the road to world glory - on this evidence - still seems difficult.
Hatton Homage Motivates Local Rivalry Contest
In the secondary fight, Lyndon Arthur beat Bradley Rea by close verdict in a outstanding all-Manchester contest to capture the European light heavyweight title.
The venue grew hushed for a profoundly moving tribute prior to the bout as 10 bells tolled in memory of Manchester's own Hatton, who died aged 46 in last month.
It was the first major televised fight night in the urban center since Hatton's passing. As the concluding sound disappeared, the stillness became a chant of "only one Hatton".
The fighting within the ring equaled the sentiment. Arthur was knocked down by a significant blow directly to the jaw in the initial stage, standing uncertainly to his footing on the referee's count.
But the red-colored shorts of the fighter soon pressed ahead again. From the other corner, the opponent - in opposing blue - was damaged soon, noticeable damage appearing under his orbital area as the duo landed hard punches.
Rea, twenty-seven, landed power punches but Arthur, thirty-four, responded in kind with stinging uppercuts as the intensity rarely dropped over the full distance.
Arthur barely secured the decision with scoring tallies of even score, narrow lead and 115-112, but both fighters were determined and courageous, exactly what their inspiration Hatton embodied.
