UK light-heavyweight Buatsi made a winning yet disappointing start to life under recent management with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level appeared to earn him a majority decision in a competitive 10-round fight at the Manchester venue.
But the challenger had his moments, landing some telling single shots in a fight where the approaches never quite clicked, with excessive holding disrupting the contest.
The officials judged it 96-94 for to Buatsi, with the final judge a even score.
"It wasn't my finest showing but what defines champions? They succeed," Buatsi said in the ring as he was greeted with disapproval 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 claim a 20th career victory.
Several boxing experts believed the challenger, 31, deserved the decision but the contender experienced the second defeat of his 28-bout career.
Buatsi Secures Win in Uneventful Match
Buatsi's progress has stalled in recent times through management issues and considerable time of inactivity.
Once tipped as the rising talent of the British fight scene, he now finds himself trying to realize his potential - perhaps in what seems like a last chance - under recent support.
He started carefully, with neither fighter prepared to be aggressive in a calculated opening few rounds.
Parker, whose sole prior loss came at super-middleweight against his former opponent in two years ago after damaging his hand during the bout, was participating in his second fight at light-heavyweight.
By the middle rounds, Parker had made it competitive, causing problems for Buatsi, who operated with a tight guard to narrowly win the more effective periods.
The crowd's patience diminished amid frequent holding, with Parker falling to the floor various instances during clinches.
Parker finished the stronger, but several stanzas were challenging to assess. Nevertheless, previous titleholder the boxing analyst - commentating on the broadcast network - had it strongly leaning for the challenger, scoring for Buatsi just one round.
Buatsi moves on, but with the presence of heavy hitter David Benavidez, and Russian star Dmitry Bivol dominating the weight class, the path to championship success - based on this performance - still appears challenging.
Ricky Hatton Tribute Inspires Local Rivalry Contest
In the co-main event, Lyndon Arthur defeated Rea by divided decision in a terrific all-Manchester battle to capture the continental belt.
The venue became quiet for a deeply poignant tribute ahead of the contest as ten bells sounded in honor of local hero Hatton, who succumbed at age 46 in recently.
It was the first major televised fight night in the urban center since Hatton's passing. As the last bell disappeared, the silence became a shout of "there's just one Hatton".
The action inside the ropes reflected the sentiment. Arthur was sent to the canvas by a powerful punch flush on the chin in the second round, getting up unsteadily to his footing on the referee's count.
But the Manchester United-red shorts of Arthur soon pressed ahead again. On the opposite side, the opponent - in competitive blue - was injured quickly, noticeable damage forming under his eye as the fighters landed powerful shots.
Rea, 27, connected with strong blows but Arthur, 34, fought fire with fire with stinging uppercuts as the intensity seldom decreased over twelve rounds.
The victor barely secured the result with judges scorecards of draw, close margin and 115-112, but the two athletes were relentless and courageous, all the qualities their hero Hatton embodied.
