UK light heavyweight Buatsi earned a win yet unimpressive start to his career under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's punch output appeared to earn him a judges' verdict in a tight ten-round bout at the Co-op Live Arena.
But the challenger had his moments, delivering effective individual punches in a fight where the techniques never quite clicked, with excessive holding marring the fight.
The officials scored it 96-94 to the winner, with the remaining official a even score.
"It wasn't my finest showing but what do champions do? They win," Buatsi stated in the ring as he was greeted with boos from the audience.
The Londoner got back to winning after his first professional defeat - an thrilling contest with Callum Smith in last winter - to secure a twentieth professional win.
Various analysts felt Parker, thirty-one, merited the decision but the contender endured the second loss of his 28-bout professional journey.
Buatsi Secures Win in Uneventful Match
His career development has stalled in recent years through management issues and long spells of inactivity.
Once tipped as the next star of the British fight scene, he now finds himself trying to fulfil that early promise - perhaps in what appears to be a final roll of the dice - under new promotional backing.
He opened tentatively, with both competitors willing to be aggressive in a tentative early stages.
The challenger, whose single earlier setback came at the lower weight class against John Ryder in two years ago after breaking his hand mid-fight, was participating in his second bout at the higher weight class.
By the middle rounds, Parker had stayed in contention, creating difficulties for Buatsi, who utilized a protective stance to edge the better rounds.
The spectators' acceptance decreased because of constant clinching, with the challenger going down various instances during grappling.
The underdog ended stronger, but many rounds were difficult to score. Nevertheless, previous titleholder Carl Frampton - commentating on the broadcast network - had it significantly in favor for Parker, awarding Buatsi just only one stanza.
The victor progresses, but with the presence of heavy hitter Benavidez, and Russian star Dmitry Bivol ruling the division, the path to championship success - on this evidence - still looks steep.
Ricky Hatton Memorial Motivates Manchester Derby Fight
In the supporting bout, Arthur defeated Rea by split-decision in a excellent all-Manchester contest to capture the European light heavyweight championship.
The stadium grew hushed for a profoundly moving tribute before the fight as ten bells sounded in remembrance of local hero Hatton, who passed away at age 46 in last month.
It was the first major televised match card in the city since Hatton's death. As the concluding sound disappeared, the stillness transitioned to a chant of "there's just one Ricky Hatton".
The competition during the bout reflected the feeling. The eventual winner was floored by a significant blow squarely on the face in the early round, getting up unsteadily to his position on the referee's count.
But the Manchester United-red attire of the fighter soon advanced again. From the other corner, the opponent - in rival City blue - was damaged quickly, noticeable damage forming under his face as the duo exchanged powerful shots.
Rea, 27, delivered effective strikes but Arthur, 34, responded in kind with effective uppercuts as the action hardly diminished over the full distance.
The victor barely secured the verdict with scoring tallies of 114-114, 115-113 and clearer margin, but both fighters were relentless and brave, all the qualities their hero Hatton embodied.
