UK light-heavyweight Buatsi secured a victory yet underwhelming start to his career under new promoters with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's activity level appeared to earn him a split decision in a competitive 10-round contest at the Co-op Live Arena.
But the challenger found success, landing some telling clean blows in a match where the styles never quite clicked, with constant grabbing disrupting the contest.
Two judges judged it 96-94 for to Buatsi, with the third a 95-95 draw.
"It wasn't my greatest showing but what do champions do? They prevail," the victor said in the ring as he was met by disapproval from the crowd.
The British fighter returned to winning ways after his first professional defeat - an thrilling contest with his previous opponent in last winter - to secure a twentieth professional win.
Several boxing experts thought Parker, 31, deserved the win but the British boxer endured the second defeat of his 28-fight career.
Buatsi Earns Win in Uneventful Encounter
His career development has slowed in recent times through promotional disputes and extended periods of inactivity.
Earlier forecast as the rising talent of British boxing, he now is positioned trying to fulfil that early promise - possibly in what appears to be a last chance - under fresh management.
He started carefully, with both competitors prepared to overcommit in a calculated opening few rounds.
Parker, whose single earlier setback came at the lower weight class against John Ryder in 2022 after suffering a hand injury mid-fight, was competing in only his second fight at light-heavyweight.
By the halfway stage, Parker had made it competitive, making life awkward for Buatsi, who operated with a tight guard to narrowly win the more effective stanzas.
The spectators' acceptance wore thin because of regular grabbing, with Parker going down several times during close exchanges.
The underdog finished the stronger, but several stanzas were challenging to assess. However, former world champion the boxing analyst - working with the broadcast network - had it particularly wide for Parker, giving Buatsi just a single round.
Buatsi advances, but with the likes of hard hitter Benavidez, and Russian star Dmitry Bivol leading the category, the journey to titles - judging by this showing - still seems difficult.
Ricky Hatton Homage Motivates Manchester Derby Battle
In the co-main event, Lyndon Arthur beat Bradley Rea by divided decision in a excellent all-Manchester fight to secure the continental title.
The stadium became quiet for a deeply poignant homage before the fight as a bell ceremony sounded in remembrance of local hero Ricky Hatton, who succumbed aged 46 in last month.
It was the premier televised fight night in the location since Hatton's death. As the concluding sound faded, the stillness transitioned to a shout of "there's just one Hatton".
The action inside the ropes matched the emotion. The eventual winner was floored by a significant blow squarely on the jaw in the second round, rising shakily to his position on the count of eight.
But the red-colored equipment of the fighter soon pressed ahead again. On the opposite side, Rea - in opposing blue - was marked up quickly, heavy swelling developing under his orbital area as the duo traded punishing blows.
Rea, twenty-seven, connected with strong blows but the champion, 34, fought fire with fire with stinging uppercuts as the pace hardly diminished over twelve rounds.
Arthur edged the verdict with scoring tallies of draw, close margin and wider gap, but the two athletes were persistent and full of heart, all the qualities their idol Hatton stood for.
