British light heavyweight Buatsi secured a victory yet disappointing debut to life under fresh promotional backing with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's work rate likely gained him a judges' verdict in a competitive ten-round fight at the boxing arena.
But the challenger had his moments, delivering effective single shots in a contest where the approaches didn't complement each other, with excessive holding disrupting the fight.
The scoring judges scored it 96-94 to the winner, with the third a even score.
"It wasn't my best showing but what defines champions? They succeed," the victor said in the ringside as he was faced negative reactions from the crowd.
The British fighter bounced back after his first professional defeat - an memorable fight with Callum Smith in February - to earn a 20th career victory.
Several boxing experts felt the challenger, 31, deserved the win but the British boxer experienced the second setback of his 28-bout career.
Buatsi Claims Victory in Dull Encounter
Buatsi's progress has plateaued in recent years through contract problems and considerable time of inactivity.
Earlier forecast as the next star of the British fight scene, he now is positioned trying to realize his potential - maybe in what seems like a final roll of the dice - under new promotional backing.
He opened tentatively, with both competitors prepared to overcommit in a calculated initial rounds.
Parker, whose sole prior loss came at super-middleweight against John Ryder in 2022 after suffering a hand injury in the contest, was participating in his second bout at light heavyweight.
By the middle rounds, Parker had stayed in contention, making life awkward for the favorite, who utilized a protective stance to barely take the cleaner stanzas.
The crowd's patience wore thin because of frequent holding, with Parker falling to the floor several times during clinches.
The underdog ended stronger, but multiple periods were difficult to score. Although, ex-champion Carl Frampton - working with Dazn - had it particularly wide for Parker, awarding Buatsi just only one stanza.
Buatsi progresses, but with the likes of hard hitter Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the path to championship success - based on this performance - still appears challenging.
Ricky Hatton Homage Inspires Manchester Derby Fight
In the supporting bout, Lyndon Arthur beat Bradley Rea by split-decision in a terrific Manchester vs Manchester contest to win the European light heavyweight title.
The arena grew hushed for a deeply poignant tribute before the fight as ten bells sounded in memory of the city's native Ricky Hatton, who succumbed at age 46 in last month.
It was the initial significant broadcast match card in the location since Hatton's passing. As the concluding sound disappeared, the stillness transitioned to a shout of "there's just one Hatton".
The action within the ring matched the sentiment. Arthur was floored by a left hook directly to the face in the initial stage, rising shakily to his footing on the eight count.
But the red-colored equipment of Arthur soon advanced again. From the other corner, Rea - in rival City blue - was marked up soon, noticeable damage developing under his eye as the pair traded hard punches.
The challenger, twenty-seven, connected with strong blows but the champion, 34, fought fire with fire with powerful upward punches as the action rarely dropped over the full distance.
Arthur narrowly won the result with judges scorecards of 114-114, close margin and 115-112, but the two athletes were relentless and full of heart, everything their idol Hatton stood for.
