UK light heavyweight Buatsi earned a win yet disappointing beginning to life under fresh promotional backing with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level seemingly secured him a judges' verdict in a close 10-round bout at the Co-op Live Arena.
But Parker landed significant shots, landing some telling clean blows in a fight where the approaches failed to mesh, with excessive holding marring the contest.
Two judges had it 96-94 for to Buatsi, with the third a 95-95.
"It wasn't my finest performance but what do champions do? They succeed," Buatsi commented in the arena as he was met by boos from the audience.
The British fighter got back to winning after his maiden career setback - an thrilling contest with his previous opponent in last winter - to secure a 20th career victory.
Several boxing experts thought Parker, thirty-one, deserved the victory but the Derbyshire fighter suffered the second loss of his 28-match career.
Buatsi Secures Win in Slow Encounter
Buatsi's progress has plateaued in recent times through promotional disputes and considerable time of inactivity.
Earlier forecast as the next star of British boxing, he now stands trying to achieve expectations - maybe in what seems like a last chance - under recent support.
He began cautiously, with neither fighter willing to overcommit in a calculated initial rounds.
The challenger, whose only previous defeat came at super-middleweight against his former opponent in 2022 after breaking his hand in the contest, was making just his second appearance at light heavyweight.
By the middle rounds, Parker had kept it close, causing problems for Buatsi, who utilized a solid defense to edge the more effective stanzas.
The audience's tolerance decreased during regular grabbing, with Parker falling to the floor several times during clinches.
The underdog ended stronger, but many rounds were hard to judge. Although, former world champion Carl Frampton - working with Dazn - had it strongly leaning for Parker, giving Buatsi just only one stanza.
Buatsi advances, but with the likes of power puncher Benavidez, and Russian star Dmitry Bivol ruling the division, the journey to titles - on this evidence - still appears challenging.
Hatton Memorial Inspires Manchester Derby Contest
In the co-main event, Lyndon Arthur defeated Rea by split-decision in a outstanding local rivalry fight to secure the European light heavyweight championship.
The arena grew hushed for a profoundly moving memorial before the fight as 10 bells sounded in remembrance of Manchester's own Ricky Hatton, who succumbed 46 years old in September.
It was the initial significant broadcast match card in the city since the passing of Hatton. As the final chime disappeared, the stillness transitioned to a shout of "only one Hatton".
The fighting inside the ropes matched the sentiment. The eventual winner was sent to the canvas by a significant blow squarely on the jaw in the early round, rising shakily to his position on the count of eight.
But the traditional red shorts of Arthur soon pressed ahead again. From the other corner, the opponent - in competitive blue - was marked up soon, significant bruising appearing under his face as the duo exchanged hard punches.
The challenger, twenty-seven, landed power punches but Arthur, thirty-four, matched the intensity with powerful upward punches as the action rarely dropped over the full distance.
Arthur barely secured the verdict with judges scorecards of even score, 115-113 and 115-112, but the two athletes were determined and brave, exactly what their inspiration the legend stood for.
