UK light-heavyweight Buatsi earned a win yet underwhelming start to his career under new promoters with a decision win over Zach Parker in Manchester.
The Olympic medal winner's activity level appeared to earn him a majority decision in a competitive 10-round fight at the boxing arena.
But the challenger had his moments, landing some telling clean blows in a match where the styles didn't complement each other, with constant grabbing marring the action.
The scoring judges had it 96-94 for to Buatsi, with the remaining official a even score.
"It wasn't my finest display but what do champions do? They win," the victor said in the ringside as he was greeted with negative reactions from the spectators.
The British fighter returned to winning ways after his initial pro loss - an thrilling contest with Callum Smith in last winter - to earn a 20th pro success.
Several boxing experts believed Parker, thirty-one, merited the win but the contender suffered the second loss of his 28-bout professional journey.
The Champion Earns Triumph in Uneventful Affair
His career development has plateaued in the past few years through promotional disputes and long spells of inactivity.
Previously predicted as the rising talent of UK boxing, he now finds himself trying to fulfil that early promise - perhaps in what feels like a final roll of the dice - under new promotional backing.
He opened tentatively, with both competitors willing to overcommit in a tentative initial rounds.
Parker, whose sole prior loss came at super-middleweight against his former opponent in two years ago after breaking his hand mid-fight, was participating in his second fight at the higher weight class.
By the middle rounds, Parker had stayed in contention, creating difficulties for the favorite, who utilized a solid defense to barely take the more effective periods.
The audience's tolerance wore thin because of constant clinching, with the challenger slipping to the canvas various instances during clinches.
Parker closed well, but several stanzas were challenging to assess. Nevertheless, previous titleholder the boxing analyst - working with the broadcast network - had it strongly leaning for Parker, giving Buatsi just a single round.
The victor advances, but with the likes of power puncher Benavidez, and Eastern European fighter Bivol leading the category, the path to championship success - on this evidence - still seems difficult.
Ricky Hatton Homage Fuels All-Manchester Fight
In the co-main event, Arthur beat Bradley Rea by split-decision in a outstanding Manchester vs Manchester battle to secure the continental belt.
The arena became quiet for a profoundly moving tribute before the fight as ten bells rang in memory of the city's native Hatton, who died 46 years old in September.
It was the first major televised match card in the urban center since Hatton's death. As the concluding sound disappeared, the stillness transitioned to a roar of "only one Hatton".
The competition inside the ropes reflected the feeling. The eventual winner was sent to the canvas by a left hook flush on the jaw in the second round, getting up unsteadily to his footing on the count of eight.
But the traditional red attire of Arthur soon came forward again. On the opposite side, the opponent - in opposing blue - was damaged quickly, heavy swelling developing under his orbital area as the fighters landed punishing blows.
Rea, 27, delivered effective strikes but Arthur, thirty-four, matched the intensity with powerful upward punches as the action seldom decreased over the full distance.
The victor edged the verdict with scoring tallies of even score, narrow lead and clearer margin, but both fighters were determined and courageous, exactly what their inspiration the legend represented.
