British light-heavyweight Buatsi made a winning yet underwhelming beginning to life under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic medal winner's activity level likely gained him a judges' verdict in a tight 10-round contest at the boxing arena.
But Parker had his moments, delivering effective single shots in a contest where the styles didn't complement each other, with frequent clinching marring the action.
The scoring judges scored it 96-94 for to Buatsi, with the final judge a 95-95.
"It wasn't my best showing but what do champions do? They win," the victor said in the ringside as he was faced negative reactions from the audience.
The British fighter returned to winning ways after his first professional defeat - an memorable fight with his previous opponent in last winter - to earn a 20th pro success.
Various analysts believed the challenger, 31, deserved the decision but the British boxer suffered the second defeat of his 28-match career.
The Champion Earns Win in Uneventful Affair
His career development has slowed in the past few years through contract problems and extended periods of lack of fights.
Once tipped as the rising talent of British boxing, he now is positioned trying to realize his potential - perhaps in what feels like a last chance - under new promotional backing.
He began cautiously, with the two boxers ready to take risks in a calculated initial rounds.
The challenger, whose only previous defeat came at the lower weight class against John Ryder in two years ago after breaking his hand in the contest, was making just his second appearance at the higher weight class.
By the middle rounds, the underdog had stayed in contention, creating difficulties for Buatsi, who worked behind a protective stance to barely take the more effective rounds.
The crowd's patience wore thin because of frequent holding, with the challenger falling to the floor multiple occasions during close exchanges.
Parker closed well, but multiple periods were challenging to assess. Although, previous titleholder the boxing analyst - commentating on Dazn - had it strongly leaning for Parker, giving Buatsi just one round.
Buatsi progresses, but with the caliber of power puncher Benavidez, and Russian star Bivol ruling the division, the journey to titles - judging by this showing - still appears challenging.
Ricky Hatton Tribute Fuels Manchester Derby Battle
In the supporting bout, Arthur overcame Bradley Rea by divided decision in a excellent Manchester vs Manchester battle to secure the continental belt.
The stadium became quiet for a profoundly moving memorial prior to the bout as a bell ceremony tolled in honor of the city's native Hatton, who succumbed 46 years old in recently.
It was the first major televised boxing event in the urban center since Hatton's death. As the last bell ended, the silence became a shout of "there's only one Ricky Hatton".
The competition during the bout equaled the sentiment. Arthur was floored by a significant blow directly to the jaw in the second round, standing uncertainly to his position on the referee's count.
But the Manchester United-red equipment of Arthur soon pressed ahead again. Across the ring, Rea - in opposing blue - was injured early, noticeable damage appearing under his face as the pair traded punishing blows.
Rea, twenty-seven, connected with strong blows but Arthur, 34, responded in kind with stinging uppercuts as the pace hardly diminished over 12 rounds.
Arthur narrowly won the verdict with scoring tallies of 114-114, close margin and 115-112, but both fighters were relentless and courageous, exactly what their hero the legend embodied.
