British light heavyweight Buatsi made a winning yet unimpressive start to his career under recent management with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level appeared to earn him a judges' verdict in a competitive 10-round contest at the boxing arena.
But the challenger found success, connecting with powerful individual punches in a match where the approaches failed to mesh, with frequent clinching marring the contest.
The scoring judges had it 96-94 in favor to the winner, with the third a 95-95 draw.
"It wasn't my greatest showing but what defines champions? They succeed," the victor stated in the ring as he was met by negative reactions from the audience.
The British fighter bounced back after his initial pro loss - an thrilling contest with his previous opponent in last winter - to claim a 20th pro success.
Various analysts believed Parker, thirty-one, merited the victory but the British boxer endured the second setback of his 28-fight professional journey.
The Champion Earns Win in Slow Affair
The fighter's advancement has slowed in the past few years through promotional disputes and extended periods of inactivity.
Earlier forecast as the future of UK boxing, he now is positioned trying to realize his potential - perhaps in what feels like a ultimate opportunity - under new promotional backing.
He opened tentatively, with the two boxers prepared to be aggressive in a tentative opening few rounds.
The challenger, whose only previous defeat came at super-middleweight against John Ryder in two years ago after suffering a hand injury during the bout, was making just his second appearance at light-heavyweight.
By the middle rounds, Parker had kept it close, creating difficulties for Buatsi, who operated with a tight guard to narrowly win the more effective rounds.
The audience's tolerance wore thin because of frequent holding, with Parker slipping to the canvas multiple occasions during grappling.
The underdog finished the stronger, but several stanzas were difficult to score. Nevertheless, previous titleholder the boxing analyst - commentating on the broadcast network - had it particularly wide for the challenger, scoring for Buatsi just a single round.
Buatsi moves on, but with the likes of power puncher David Benavidez, and Russian champion Dmitry Bivol ruling the division, the journey to titles - on this evidence - still appears challenging.
Hatton Memorial Inspires All-Manchester Contest
In the supporting bout, Lyndon Arthur overcame Bradley Rea by close verdict in a terrific local rivalry battle to win the European light-heavyweight championship.
The arena fell silent for a profoundly moving tribute ahead of the contest as 10 bells sounded in remembrance of Manchester's own Ricky Hatton, who passed away 46 years old in last month.
It was the initial significant broadcast match card in the urban center since the passing of Hatton. As the final chime disappeared, the stillness transitioned to a chant of "there's just one Ricky Hatton".
The fighting inside the ropes matched the emotion. The eventual winner was knocked down by a left hook directly to the face in the initial stage, getting up unsteadily to his footing on the count of eight.
But the red-colored shorts of the fighter soon came forward again. From the other corner, the opponent - in opposing blue - was marked up soon, heavy swelling appearing under his face as the pair traded powerful shots.
The challenger, twenty-seven, delivered effective strikes but the champion, thirty-four, matched the intensity with stinging uppercuts as the action hardly diminished over twelve rounds.
The victor barely secured the verdict with judges scorecards of draw, 115-113 and wider gap, but both fighters were relentless and courageous, all the qualities their inspiration the legend represented.
