UK light-heavyweight Buatsi earned a win yet underwhelming debut to life under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's work rate seemingly secured him a majority decision in a tight ten-round contest at the Manchester venue.
But Parker had his moments, connecting with powerful clean blows in a match where the styles didn't complement each other, with frequent clinching marring the fight.
The officials scored it 96-94 to Buatsi, with the third a 95-95.
"It wasn't my greatest showing but what do champions do? They win," Buatsi said in the ringside as he was faced boos from the audience.
The Londoner got back to winning after his initial pro loss - an thrilling contest with his previous opponent in last winter - to claim a 20th career victory.
Several boxing experts thought the challenger, thirty-one, merited the win but the British boxer experienced the second setback of his 28-fight career.
The Champion Earns Triumph in Dull Affair
The fighter's advancement has stalled in recent times through contract problems and extended periods of inactivity.
Earlier forecast as the future of the British fight scene, he now finds himself trying to fulfil that early promise - maybe in what feels like a final roll of the dice - under new promotional backing.
He opened tentatively, with neither fighter prepared to take risks in a cagey early stages.
The challenger, whose only previous defeat came at super-middleweight against John Ryder in two years ago after damaging his hand during the bout, was making just his second appearance at light-heavyweight.
By the middle rounds, Parker had made it competitive, making life awkward for the favorite, who operated with a solid defense to narrowly win the more effective stanzas.
The spectators' acceptance decreased amid frequent holding, with Parker going down multiple occasions during close exchanges.
The underdog finished the stronger, but many rounds were hard to judge. However, ex-champion Carl Frampton - providing analysis for Dazn - had it significantly in favor for the challenger, giving Buatsi just one round.
Buatsi progresses, but with the presence of heavy hitter Benavidez, and Eastern European fighter Bivol leading the category, the road to world glory - judging by this showing - still seems difficult.
Hatton Tribute Motivates All-Manchester Battle
In the supporting bout, Arthur overcame Bradley Rea by close verdict in a outstanding all-Manchester battle to secure the European light heavyweight title.
The stadium grew hushed for a profoundly moving memorial prior to the bout as 10 bells sounded in remembrance of local hero Hatton, who succumbed aged 46 in last month.
It was the premier televised match card in the location since Hatton's passing. As the concluding sound faded, the quiet gave way to a shout of "there's just one Ricky Hatton".
The fighting during the bout equaled the emotion. The eventual winner was floored by a significant blow flush on the jaw in the second round, getting up unsteadily to his feet on the count of eight.
But the traditional red equipment of Arthur soon pressed ahead again. From the other corner, Rea - in rival City blue - was injured quickly, significant bruising developing under his orbital area as the pair landed powerful shots.
Rea, 27, connected with strong blows but Arthur, thirty-four, fought fire with fire with powerful upward punches as the intensity hardly diminished over twelve rounds.
Arthur edged the verdict with scoring tallies of 114-114, narrow lead and clearer margin, but the two athletes were relentless and full of heart, exactly what their hero the legend embodied.
