UK light-heavyweight Buatsi secured a victory yet disappointing debut to his career under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's work rate seemingly secured him a majority decision in a tight ten-round fight at the boxing arena.
But the challenger had his moments, connecting with powerful single shots in a contest where the approaches didn't complement each other, with excessive holding marring the contest.
Two judges scored it 96-94 in favor to the winner, with the final judge a 95-95 draw.
"It wasn't my greatest showing but what do champions do? They succeed," Buatsi commented in the ringside as he was met by boos from the crowd.
The Londoner 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 believed Parker, 31, should have been awarded the win but the Derbyshire fighter endured the second loss of his 28-bout career.
The Champion Secures Win in Slow Match
His career development has slowed in the past few years through contract problems and extended periods of lack of fights.
Earlier forecast as the rising talent of UK boxing, he now stands trying to fulfil that early promise - possibly in what feels like a last chance - under new promotional backing.
He started carefully, with the two boxers prepared to take risks in a cagey opening few rounds.
Parker, whose only previous defeat came at super middleweight against his former opponent in 2022 after damaging his hand mid-fight, was competing in only his second fight at light heavyweight.
By the halfway stage, the underdog had kept it close, creating difficulties for the favorite, who operated with a solid defense to edge the better stanzas.
The crowd's patience wore thin because of frequent holding, with the challenger falling to the floor various instances during close exchanges.
The underdog ended stronger, but several stanzas were challenging to assess. Nevertheless, ex-champion Carl Frampton - working with Dazn - had it significantly in favor for Parker, awarding Buatsi just one round.
Buatsi progresses, but with the likes of hard hitter Benavidez, and Russian star Dmitry Bivol ruling the division, the path to championship success - on this evidence - still seems difficult.
Ricky Hatton Memorial Fuels Manchester Derby Fight
In the supporting bout, Lyndon Arthur beat Bradley Rea by divided decision in a terrific all-Manchester fight to win the European light-heavyweight championship.
The stadium became quiet for a deeply poignant homage prior to the bout as a bell ceremony tolled in memory of local hero Ricky Hatton, who passed away at age 46 in last month.
It was the first major televised fight night in the location since Hatton's passing. As the last bell ended, the stillness transitioned to a shout of "there's only one Ricky Hatton".
The fighting during the bout reflected the sentiment. The eventual winner was floored by a left hook squarely on the chin in the second round, getting up unsteadily to his position on the eight count.
But the red-colored equipment of Arthur soon pressed ahead again. On the opposite side, the opponent - in rival City blue - was marked up early, heavy swelling developing under his orbital area as the duo traded powerful shots.
The challenger, 27, connected with strong blows but the champion, 34, matched the intensity with powerful upward punches as the intensity seldom decreased over the full distance.
The victor barely secured the verdict with judges scorecards of even score, 115-113 and wider gap, but the two athletes were determined and full of heart, exactly what their inspiration Hatton embodied.
