British light-heavyweight Buatsi made a winning yet unimpressive debut to his career under new promoters with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's punch output appeared to earn him a majority decision in a competitive ten-round bout at the boxing arena.
But Parker had his moments, landing some telling individual punches in a fight where the approaches never quite clicked, with excessive holding marring the action.
Two judges scored it 96-94 for to Buatsi, with the final judge a 95-95.
"It wasn't my finest display but what do champions do? They prevail," the victor commented in the arena as he was greeted with disapproval from the audience.
The British fighter bounced back after his maiden career setback - an thrilling contest with Callum Smith in last winter - to earn a twentieth professional win.
Some ringside observers felt the challenger, 31, merited the win but the Derbyshire fighter endured the second setback of his 28-match professional journey.
Buatsi Earns Triumph in Slow Match
His career development has stalled in the past few years through promotional disputes and extended periods of lack of fights.
Once tipped as the future of UK boxing, he now finds himself trying to realize his potential - possibly in what appears to be a final roll of the dice - under fresh management.
He began cautiously, with the two boxers willing to take risks in a calculated opening few rounds.
The challenger, whose only previous defeat came at super middleweight against John Ryder in 2022 after suffering a hand injury in the contest, was competing in only his second bout at light-heavyweight.
By the middle rounds, the underdog had kept it close, causing problems for Buatsi, who utilized a solid defense to narrowly win the more effective stanzas.
The audience's tolerance diminished because of frequent holding, with the challenger falling to the floor multiple occasions during close exchanges.
The underdog finished the stronger, but many rounds were challenging to assess. Although, ex-champion Carl Frampton - commentating on the broadcast network - had it particularly wide for the challenger, giving Buatsi just one round.
The victor moves on, but with the presence of power puncher Benavidez, and Russian champion Bivol dominating the weight class, the road to world glory - judging by this showing - still looks steep.
Hatton Homage Inspires Local Rivalry Battle
In the co-main event, Lyndon Arthur beat Rea by close verdict in a terrific local rivalry contest to capture the European light heavyweight belt.
The venue became quiet for a profoundly moving homage before the fight as 10 bells sounded in memory of the city's native Ricky Hatton, who died aged 46 in last month.
It was the premier televised boxing event in the city since Hatton's death. As the concluding sound ended, the stillness transitioned to a chant of "only one Hatton".
The action within the ring matched the emotion. Arthur was knocked down by a significant blow flush on the jaw in the second round, rising shakily to his position on the referee's count.
But the traditional red shorts of the fighter soon pressed ahead again. On the opposite side, Rea - in competitive blue - was damaged early, noticeable damage forming under his face as the fighters exchanged powerful shots.
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.
The victor edged the decision with scoring tallies of even score, close margin and 115-112, but each competitor were determined and brave, all the qualities their inspiration Hatton represented.
