British light heavyweight Buatsi earned a win yet underwhelming debut to life under recent management with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's punch output appeared to earn him a majority decision in a tight ten-round fight at the Co-op Live Arena.
But the challenger had his moments, connecting with powerful single shots in a fight where the styles never quite clicked, with frequent clinching spoiling the contest.
Two judges judged it 96-94 for to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my best display but what defines champions? They succeed," Buatsi commented in the ring as he was greeted with boos from the crowd.
The British fighter got back to winning after his maiden career setback - an memorable fight with his previous opponent in last winter - to claim a 20th pro success.
Several boxing experts thought Parker, thirty-one, deserved the decision but the contender suffered the second defeat of his 28-bout professional journey.
The Champion Earns Victory in Slow Encounter
Buatsi's progress has plateaued in the past few years through management issues and long spells of lack of fights.
Previously predicted as the next star of British boxing, he now finds himself trying to achieve expectations - maybe in what appears to be a ultimate opportunity - under new promotional backing.
He opened tentatively, with both competitors ready to overcommit in a calculated opening few rounds.
Parker, whose only previous defeat came at super-middleweight against John Ryder in 2022 after breaking his hand in the contest, was participating in his second appearance at the higher weight class.
By the fight's midpoint, Parker had made it competitive, creating difficulties for the favorite, who utilized a tight guard to barely take the better rounds.
The spectators' acceptance diminished during regular grabbing, with the challenger falling to the floor several times during close exchanges.
The underdog closed well, but many rounds were challenging to assess. Although, previous titleholder Carl Frampton - providing analysis for Dazn - had it strongly leaning for Parker, giving Buatsi just a single round.
Buatsi progresses, but with the presence of hard hitter David Benavidez, and Russian champion Bivol leading the category, the journey to titles - on this evidence - still seems difficult.
Ricky Hatton Memorial Fuels Manchester Derby Battle
In the supporting bout, Lyndon Arthur beat Rea by divided decision in a excellent local rivalry fight to capture the continental title.
The arena became quiet for a extremely emotional homage ahead of the contest as 10 bells tolled in honor of local hero Ricky Hatton, who succumbed 46 years old in last month.
It was the initial significant broadcast boxing event in the urban center since Hatton's passing. As the concluding sound disappeared, the stillness transitioned to a chant of "there's only one Hatton".
The fighting within the ring reflected the feeling. Arthur was sent to the canvas by a left hook directly to the face in the early round, standing uncertainly to his position on the eight count.
But the Manchester United-red shorts of Arthur soon came forward again. From the other corner, Rea - in competitive blue - was damaged early, heavy swelling forming under his eye as the fighters traded punishing blows.
Rea, 27, delivered effective strikes but the champion, thirty-four, fought fire with fire with stinging uppercuts as the action rarely dropped over twelve rounds.
The victor edged the decision with judges scorecards of draw, 115-113 and wider gap, but both fighters were persistent and brave, exactly what their idol Hatton stood for.
