UK light-heavyweight Buatsi made a winning yet unimpressive beginning to his career under new promoters with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level likely gained him a split decision in a tight 10-round contest at the Co-op Live Arena.
But Parker had his moments, landing some telling clean blows in a match where the techniques failed to mesh, with frequent clinching marring the action.
The officials judged it 96-94 for to Buatsi, with the third a 95-95 draw.
"It wasn't my greatest display but what do champions do? They win," the victor said in the ringside as he was met by negative reactions from the spectators.
The British fighter got back to winning after his maiden career setback - an memorable fight with Callum Smith in last winter - to claim a twentieth professional win.
Some ringside observers believed the challenger, thirty-one, should have been awarded the victory but the British boxer endured the second defeat of his 28-fight professional journey.
Buatsi Secures Victory in Slow Match
The fighter's advancement has plateaued in the past few years through management issues and extended periods of lack of fights.
Once tipped as the next star of UK boxing, he now finds himself trying to achieve expectations - maybe in what seems like a last chance - under fresh management.
He began cautiously, with the two boxers willing to overcommit in a cagey initial rounds.
The challenger, whose single earlier setback came at the lower weight class against his former opponent in 2022 after breaking his hand mid-fight, was participating in his second bout at the higher weight class.
By the middle rounds, Parker had made it competitive, causing problems for the favorite, who utilized a solid defense to narrowly win the better periods.
The crowd's patience wore thin amid regular grabbing, with the challenger falling to the floor several times during grappling.
The underdog closed well, but many rounds were difficult to score. However, ex-champion Carl Frampton - providing analysis for the broadcast network - had it significantly in favor for Parker, scoring for Buatsi just a single round.
Buatsi advances, but with the caliber of heavy hitter Benavidez, and Russian star Bivol ruling the division, the road to world glory - on this evidence - still seems difficult.
Hatton Homage Inspires Manchester Derby Battle
In the supporting bout, Arthur defeated Bradley Rea by divided decision in a terrific all-Manchester fight to win the European light-heavyweight belt.
The venue became quiet for a profoundly moving homage prior to the bout as ten bells tolled in honor of Manchester's own Ricky Hatton, who passed away aged 46 in recently.
It was the first major televised boxing event in the urban center since Hatton's passing. As the concluding sound faded, the silence became a shout of "only one Hatton".
The action within the ring matched the emotion. Arthur was sent to the canvas by a powerful punch flush on the face in the second round, getting up unsteadily to his footing on the count of eight.
But the Manchester United-red attire of the fighter soon advanced again. Across the ring, the opponent - in opposing blue - was injured quickly, heavy swelling developing under his orbital area as the duo exchanged hard punches.
The challenger, 27, connected with strong blows but Arthur, 34, matched the intensity with effective uppercuts as the action hardly diminished over twelve rounds.
Arthur edged the result with official scores of draw, 115-113 and clearer margin, but the two athletes were persistent and full of heart, all the qualities their inspiration the legend stood for.
