UK light heavyweight Buatsi made a winning yet unimpressive debut to his career under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's punch output seemingly secured him a judges' verdict in a tight 10-round contest at the Manchester venue.
But Parker found success, connecting with powerful individual punches in a contest where the approaches failed to mesh, with constant grabbing disrupting the fight.
The officials scored it 96-94 in favor to Buatsi, with the final judge a even score.
"It wasn't my best performance but what do champions do? They succeed," the victor said in the arena as he was faced disapproval from the audience.
The Londoner bounced back after his maiden career setback - an thrilling contest with his previous opponent in last winter - to earn a 20th pro success.
Various analysts believed the challenger, thirty-one, deserved the decision but the British boxer endured the second setback of his 28-bout professional journey.
Buatsi Secures Victory in Dull Affair
His career development has stalled in recent years through promotional disputes and extended periods of lack of fights.
Once tipped as the future of British boxing, he now stands trying to fulfil that early promise - possibly in what feels like a ultimate opportunity - under recent support.
He opened tentatively, with both competitors ready to overcommit in a calculated opening few rounds.
The challenger, whose sole prior loss came at super middleweight against his former opponent in two years ago after damaging 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, making life awkward for Buatsi, who operated with a tight guard to narrowly win the cleaner stanzas.
The audience's tolerance decreased because of constant clinching, with the challenger going down several times during close exchanges.
Parker ended stronger, but many rounds were challenging to assess. Although, former world champion Carl Frampton - working with Dazn - had it particularly wide for the challenger, giving Buatsi just one round.
Buatsi moves on, but with the presence of hard hitter David Benavidez, and Russian champion Dmitry Bivol leading the category, the path to championship success - judging by this showing - still appears challenging.
Ricky Hatton Homage Motivates Local Rivalry Fight
In the supporting bout, Lyndon Arthur beat Bradley Rea by split-decision in a outstanding Manchester vs Manchester contest to win the European light heavyweight title.
The stadium grew hushed for a extremely emotional homage before the fight as ten bells tolled in memory of the city's native Ricky Hatton, who passed away aged 46 in last month.
It was the initial significant broadcast boxing event in the location since Hatton's passing. As the final chime faded, the stillness transitioned to a chant of "there's just one Ricky Hatton".
The competition inside the ropes equaled the feeling. Arthur was knocked down by a powerful punch squarely on the jaw in the initial stage, standing uncertainly to his feet on the count of eight.
But the Manchester United-red shorts of Arthur soon advanced again. On the opposite side, Rea - in rival City blue - was marked up early, significant bruising appearing under his face as the fighters traded hard punches.
Rea, 27, landed power punches but Arthur, 34, fought fire with fire with stinging uppercuts as the intensity seldom decreased over twelve rounds.
The victor narrowly won the result with official scores of draw, 115-113 and 115-112, but both fighters were persistent and courageous, exactly what their idol the legend represented.
