British light-heavyweight Buatsi earned a win yet unimpressive beginning to life under fresh promotional backing with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's work rate seemingly secured him a majority decision in a close 10-round bout at the Manchester venue.
But the challenger had his moments, landing some telling clean blows in a match where the styles never quite clicked, with constant grabbing marring the action.
Two judges scored it 96-94 in favor to Buatsi, with the third a 95-95.
"It wasn't my best display but what defines champions? They win," Buatsi said in the ring as he was met by disapproval from the audience.
The British fighter got back to winning after his initial pro loss - an epic battle with his previous opponent in last winter - to claim a 20th career victory.
Several boxing experts felt the challenger, thirty-one, should have been awarded the decision but the British boxer endured the second setback of his 28-fight professional journey.
Buatsi Secures Triumph in Dull Encounter
The fighter's advancement has stalled in recent times through contract problems and long spells of lack of fights.
Once tipped as the next star of British boxing, he now is positioned trying to achieve expectations - possibly in what seems like a last chance - under fresh management.
He began cautiously, with the two boxers ready to overcommit in a calculated initial rounds.
Parker, whose single earlier setback came at super-middleweight against John Ryder in two years ago after damaging his hand during the bout, was competing in only his second appearance at light heavyweight.
By the fight's midpoint, Parker had made it competitive, making life awkward for Buatsi, who operated with a tight guard to edge the cleaner rounds.
The spectators' acceptance diminished because of constant clinching, with the challenger going down several times during grappling.
The underdog closed well, but multiple periods were hard to judge. Although, former world champion the boxing analyst - commentating on Dazn - had it strongly leaning for the challenger, scoring for Buatsi just a single round.
The victor advances, but with the likes of heavy hitter Benavidez, and Russian star Dmitry Bivol ruling the division, the journey to titles - based on this performance - still seems difficult.
Hatton Memorial Inspires Manchester Derby Contest
In the secondary fight, Arthur beat Bradley Rea by divided decision in a excellent all-Manchester fight to capture the European light heavyweight belt.
The stadium became quiet for a deeply poignant homage before the fight as a bell ceremony tolled in honor of Manchester's own Hatton, who passed away aged 46 in last month.
It was the premier televised boxing event in the city since Hatton's passing. As the last bell faded, the quiet transitioned to a shout of "only one Ricky Hatton".
The competition inside the ropes reflected the sentiment. The eventual winner was sent to the canvas by a powerful punch squarely on the chin in the early round, getting up unsteadily to his footing on the eight count.
But the Manchester United-red equipment of the fighter soon pressed ahead again. On the opposite side, Rea - in opposing blue - was damaged quickly, noticeable damage forming under his eye as the duo traded punishing blows.
Rea, twenty-seven, connected with strong blows but the champion, 34, responded in kind with effective uppercuts as the pace rarely dropped over twelve rounds.
The victor barely secured the result with judges scorecards of 114-114, 115-113 and clearer margin, but the two athletes were determined and full of heart, exactly what their inspiration Hatton stood for.
