British light heavyweight Buatsi secured a victory yet underwhelming start to his career under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's activity level likely gained him a majority decision in a tight 10-round fight at the Manchester venue.
But Parker landed significant shots, delivering effective single shots in a match where the styles didn't complement each other, with frequent clinching marring the action.
Two judges judged it 96-94 to the winner, with the final judge a even score.
"It wasn't my finest performance but how do champions respond? They prevail," Buatsi stated in the arena as he was met by negative reactions from the crowd.
The Londoner bounced back after his initial pro loss - an epic battle with his previous opponent in February - to claim a 20th career victory.
Several boxing experts believed the challenger, 31, merited the decision but the British boxer experienced the second setback of his 28-match professional journey.
The Champion Claims Victory in Dull Affair
Buatsi's progress has slowed in recent times through contract problems and extended periods of inactivity.
Previously predicted as the future of UK boxing, he now finds himself trying to achieve expectations - maybe in what feels like a last chance - under recent support.
He opened tentatively, with the two boxers ready to take risks in a calculated opening few rounds.
Parker, whose sole prior loss came at super middleweight against John Ryder in 2022 after breaking his hand in the contest, was participating in his second bout at the higher weight class.
By the middle rounds, Parker had made it competitive, creating difficulties for Buatsi, who utilized a solid defense to barely take the more effective periods.
The crowd's patience wore thin during constant clinching, with Parker slipping to the canvas various instances during grappling.
Parker finished the stronger, but multiple periods were difficult to score. However, previous titleholder Carl Frampton - providing analysis for Dazn - had it significantly in favor for the challenger, scoring for Buatsi just only one stanza.
Buatsi moves on, but with the caliber of power puncher David Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the path to championship success - judging by this showing - still appears challenging.
Ricky Hatton Tribute Fuels Local Rivalry Contest
In the supporting bout, Lyndon Arthur overcame Bradley Rea by split-decision in a terrific Manchester vs Manchester contest to capture the continental belt.
The stadium became quiet for a extremely emotional tribute ahead of the contest as 10 bells tolled in honor of Manchester's own Hatton, who died at age 46 in September.
It was the first major televised boxing event in the city since Hatton's death. As the concluding sound ended, the stillness transitioned to a shout of "there's just one Hatton".
The fighting during the bout reflected the feeling. Arthur was sent to the canvas by a powerful punch squarely on the chin in the second round, standing uncertainly to his footing on the referee's count.
But the red-colored equipment of the fighter soon advanced again. Across the ring, Rea - in competitive blue - was damaged quickly, significant bruising developing under his orbital area as the duo traded punishing blows.
The challenger, twenty-seven, delivered effective strikes but the champion, 34, matched the intensity with powerful upward punches as the pace rarely dropped over the full distance.
The victor barely secured the decision with judges scorecards of even score, close margin and clearer margin, but each competitor were persistent and brave, all the qualities their inspiration the legend stood for.
