UK light-heavyweight Buatsi earned a win yet disappointing start to life under new promoters with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's work rate likely gained him a split decision in a close 10-round bout at the Manchester venue.
But Parker found success, delivering effective individual punches in a match where the styles failed to mesh, with frequent clinching spoiling the action.
The scoring judges judged it 96-94 to Buatsi, with the remaining official a 95-95.
"It wasn't my finest display but what do champions do? They prevail," the victor said in the ringside as he was greeted with disapproval from the audience.
The Londoner got back to winning after his first professional defeat - an epic battle with his previous opponent in last winter - to secure a 20th career victory.
Various analysts thought Parker, thirty-one, merited the victory but the British boxer endured the second defeat of his 28-fight professional journey.
Buatsi Claims Triumph in Dull Match
The fighter's advancement has stalled in the past few years through promotional disputes and considerable time of inactivity.
Once tipped as the future of UK boxing, he now stands trying to achieve expectations - possibly in what feels like a ultimate opportunity - under new promotional backing.
He began cautiously, with both competitors ready to be aggressive in a cagey early stages.
The challenger, whose sole prior loss came at the lower weight class against his former opponent in 2022 after suffering a hand injury during the bout, was making just his second appearance at light heavyweight.
By the middle rounds, the underdog had made it competitive, creating difficulties for the favorite, who worked behind a solid defense to narrowly win the cleaner stanzas.
The audience's tolerance decreased amid constant clinching, with Parker slipping to the canvas several times during close exchanges.
Parker closed well, but several stanzas were difficult to score. Although, previous titleholder Carl Frampton - providing analysis for the broadcast network - had it strongly leaning for Parker, giving Buatsi just one round.
Buatsi advances, but with the caliber of hard hitter Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the journey to titles - on this evidence - still appears challenging.
Ricky Hatton Tribute Inspires Local Rivalry Contest
In the secondary fight, Lyndon Arthur defeated Bradley Rea by divided decision in a excellent local rivalry battle to secure the European light-heavyweight title.
The venue fell silent for a deeply poignant homage prior to the bout as ten bells sounded in remembrance of the city's native Hatton, who succumbed at age 46 in last month.
It was the initial significant broadcast boxing event in the urban center since the passing of Hatton. As the final chime ended, the stillness transitioned to a roar of "there's only one Ricky Hatton".
The fighting within the ring equaled the sentiment. The eventual winner was floored by a significant blow squarely on the chin in the initial stage, rising shakily to his feet on the eight count.
But the traditional red shorts of Arthur soon pressed ahead again. From the other corner, Rea - in opposing blue - was marked up soon, noticeable damage developing under his eye as the pair landed hard punches.
Rea, 27, delivered effective strikes but Arthur, thirty-four, fought fire with fire with stinging uppercuts as the pace seldom decreased over twelve rounds.
The victor edged the verdict with official scores of draw, 115-113 and 115-112, but each competitor were determined and brave, everything their inspiration Hatton embodied.
