UK light heavyweight Buatsi earned a win yet unimpressive beginning to life under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's punch output appeared to earn him a judges' verdict in a competitive 10-round bout at the Manchester venue.
But Parker found success, landing some telling individual punches in a contest where the styles failed to mesh, with frequent clinching marring the action.
The scoring judges scored it 96-94 in favor to Buatsi, with the final judge a 95-95 draw.
"It wasn't my best display but what defines champions? They prevail," the victor said in the arena as he was greeted with negative reactions from the audience.
The Londoner returned to winning ways after his first professional defeat - an epic battle with his previous opponent in February - to earn a twentieth professional win.
Several boxing experts felt the challenger, thirty-one, deserved the win but the British boxer suffered the second loss of his 28-bout career.
Buatsi Secures Triumph in Slow Encounter
The fighter's advancement has plateaued in recent times through promotional disputes and extended periods of inactivity.
Previously predicted as the future of UK boxing, he now finds himself trying to fulfil that early promise - possibly in what feels like a last chance - under recent support.
He began cautiously, with the two boxers prepared to be aggressive in a calculated initial rounds.
Parker, whose single earlier setback came at super middleweight against his former opponent in two years ago after breaking his hand during the bout, was competing in only his second bout at the higher weight class.
By the halfway stage, Parker had made it competitive, creating difficulties for the favorite, who operated with a protective stance to barely take the better rounds.
The spectators' acceptance decreased during constant clinching, with the challenger going down several times during grappling.
The underdog finished the stronger, but multiple periods were challenging to assess. However, former world champion 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 hard hitter David Benavidez, and Russian star Dmitry Bivol leading the category, the path to championship success - on this evidence - still appears challenging.
Ricky Hatton Homage Inspires Local Rivalry Fight
In the secondary fight, Lyndon Arthur beat Bradley Rea by divided decision in a excellent Manchester vs Manchester fight to capture the European light-heavyweight title.
The arena fell silent for a extremely emotional tribute prior to the bout as a bell ceremony rang in remembrance of local hero Hatton, who passed away 46 years old in September.
It was the initial significant broadcast match card in the city since Hatton's passing. As the last bell faded, the silence transitioned to a roar of "there's only one Hatton".
The competition inside the ropes reflected the feeling. Arthur was floored by a left hook flush on the face in the early round, standing uncertainly to his footing on the count of eight.
But the Manchester United-red equipment of Arthur soon pressed ahead again. On the opposite side, the opponent - in opposing blue - was marked up quickly, noticeable damage forming under his orbital area as the pair traded punishing blows.
Rea, twenty-seven, landed power punches but the champion, 34, responded in kind with powerful upward punches as the action rarely dropped over 12 rounds.
Arthur barely secured the result with judges scorecards of even score, narrow lead and clearer margin, but each competitor were persistent and brave, everything their inspiration the legend stood for.
