British light-heavyweight Buatsi made a winning yet underwhelming start to his career under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's punch output likely gained him a judges' verdict in a tight ten-round bout at the boxing arena.
But the challenger had his moments, connecting with powerful clean blows in a match where the styles didn't complement each other, with constant grabbing marring the action.
Two judges had it 96-94 in favor to the winner, with the third a 95-95.
"It wasn't my best performance but what defines champions? They prevail," the victor commented in the ring as he was greeted with disapproval from the audience.
The British fighter got back to winning after his first professional defeat - an epic battle with his previous opponent in last winter - to earn a twentieth professional win.
Several boxing experts believed Parker, 31, should have been awarded the victory but the Derbyshire fighter suffered the second loss of his 28-fight career.
Buatsi Claims Triumph in Slow Encounter
The fighter's advancement has stalled in recent years through management issues and extended periods of lack of fights.
Earlier forecast as the future of British boxing, he now finds himself trying to realize his potential - perhaps in what feels like a last chance - under recent support.
He began cautiously, with the two boxers willing to overcommit in a calculated opening few rounds.
The challenger, whose single earlier setback came at super-middleweight against John Ryder in two years ago after suffering a hand injury during the bout, was competing in only his second bout at light-heavyweight.
By the fight's midpoint, Parker had kept it close, causing problems for the favorite, who worked behind a solid defense to edge the cleaner periods.
The audience's tolerance decreased amid constant clinching, with the challenger falling to the floor multiple occasions during grappling.
Parker finished the stronger, but many rounds were hard to judge. However, former world champion the boxing analyst - providing analysis for the broadcast network - had it significantly in favor for Parker, awarding Buatsi just only one stanza.
Buatsi progresses, but with the likes of hard hitter Benavidez, and Russian champion Dmitry Bivol ruling the division, the path to championship success - on this evidence - still looks steep.
Ricky Hatton Homage Inspires All-Manchester Battle
In the supporting bout, Lyndon Arthur defeated Rea by close verdict in a excellent Manchester vs Manchester contest to capture the European light-heavyweight belt.
The arena grew hushed for a profoundly moving homage prior to the bout as a bell ceremony tolled in memory of local hero Ricky Hatton, who succumbed at age 46 in September.
It was the premier televised match card in the location since Hatton's death. As the concluding sound disappeared, the stillness transitioned to a shout of "there's only one Hatton".
The action within the ring matched the emotion. The eventual winner was floored by a significant blow flush on the face in the second round, rising shakily to his footing on the count of eight.
But the traditional red equipment of Arthur soon came forward again. On the opposite side, the opponent - in competitive blue - was injured early, heavy swelling appearing under his eye as the pair exchanged punishing blows.
The challenger, twenty-seven, landed power punches but Arthur, 34, fought fire with fire with powerful upward punches as the action hardly diminished over 12 rounds.
Arthur narrowly won the verdict with judges scorecards of even score, narrow lead and 115-112, but the two athletes were relentless and brave, all the qualities their inspiration the legend embodied.
