UK light-heavyweight Buatsi made a winning yet disappointing beginning to his career under fresh promotional backing with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level likely gained him a majority decision in a tight ten-round bout at the Co-op Live Arena.
But Parker had his moments, landing some telling clean blows in a fight where the approaches failed to mesh, with constant grabbing disrupting the fight.
The officials had it 96-94 in favor to the winner, with the remaining official a 95-95 draw.
"It wasn't my greatest showing but what do champions do? They prevail," Buatsi said in the arena as he was greeted with negative reactions from the audience.
The Londoner bounced back after his initial pro loss - an memorable fight with Callum Smith in February - to claim a twentieth professional win.
Some ringside observers felt the challenger, 31, deserved the victory but the contender suffered the second setback of his 28-match career.
The Champion Claims Triumph in Dull Encounter
Buatsi's progress has stalled in the past few years through promotional disputes and extended periods of inactivity.
Earlier forecast as the next star of the British fight scene, he now is positioned trying to achieve expectations - possibly in what seems like a last chance - under new promotional backing.
He opened tentatively, with the two boxers willing to be aggressive in a cagey opening few rounds.
The challenger, whose single earlier setback came at the lower weight class against John Ryder in 2022 after suffering a hand injury in the contest, was making just his second bout at light heavyweight.
By the halfway stage, the underdog had kept it close, causing problems for the favorite, who worked behind a solid defense to narrowly win the cleaner stanzas.
The spectators' acceptance decreased because of frequent holding, with Parker going down multiple occasions during clinches.
Parker closed well, but multiple periods were hard to judge. Although, ex-champion Carl Frampton - working with Dazn - had it particularly wide for the challenger, giving Buatsi just only one stanza.
Buatsi advances, but with the presence of hard hitter Benavidez, and Russian champion Bivol dominating the weight class, the road to world glory - judging by this showing - still seems difficult.
Ricky Hatton Homage Motivates Local Rivalry Battle
In the secondary fight, Lyndon Arthur overcame Rea by split-decision in a outstanding all-Manchester contest to win the European light heavyweight championship.
The venue became quiet for a deeply poignant homage prior to the bout as 10 bells tolled in memory of the city's native Ricky Hatton, who passed away at age 46 in last month.
It was the initial significant broadcast fight night in the location since Hatton's passing. As the concluding sound faded, the silence transitioned to a chant of "there's only one Hatton".
The action during the bout equaled the sentiment. The eventual winner was floored by a significant blow squarely on the jaw in the early round, standing uncertainly to his position on the eight count.
But the Manchester United-red attire of Arthur soon came forward again. Across the ring, Rea - in competitive blue - was marked up quickly, heavy swelling appearing under his face as the pair landed powerful shots.
Rea, 27, delivered effective strikes but the champion, thirty-four, matched the intensity with stinging uppercuts as the intensity rarely dropped over the full distance.
Arthur narrowly won the result with judges scorecards of draw, close margin and wider gap, but both fighters were determined and courageous, exactly what their idol the legend represented.
