British light-heavyweight Buatsi secured a victory yet disappointing beginning to life under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's punch output appeared to earn him a majority decision in a competitive 10-round contest at the boxing arena.
But Parker found success, landing some telling single shots in a contest where the styles failed to mesh, with excessive holding marring the action.
Two judges judged it 96-94 for to Buatsi, with the third a 95-95 draw.
"It wasn't my finest showing but what do champions do? They succeed," the victor said in the ringside as he was greeted with boos from the audience.
The Londoner bounced back after his maiden career setback - an thrilling contest with Callum Smith in last winter - to earn a 20th pro success.
Some ringside observers felt the challenger, thirty-one, should have been awarded the win but the contender suffered the second setback of his 28-bout professional journey.
Buatsi Claims Triumph in Uneventful Affair
The fighter's advancement has stalled in recent years through contract problems and long spells of inactivity.
Earlier forecast as the next star of UK boxing, he now finds himself trying to achieve expectations - maybe in what seems like a ultimate opportunity - under fresh management.
He began cautiously, with neither fighter ready to be aggressive in a tentative initial rounds.
Parker, whose sole prior loss came at super-middleweight against John Ryder in 2022 after damaging his hand mid-fight, was participating in his second appearance at the higher weight class.
By the fight's midpoint, Parker had made it competitive, making life awkward for Buatsi, who operated with a tight guard to narrowly win the more effective stanzas.
The crowd's patience decreased during constant clinching, with Parker going down multiple occasions during grappling.
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, awarding Buatsi just only one stanza.
Buatsi progresses, but with the likes of heavy hitter Benavidez, and Russian star Bivol dominating the weight class, the path to championship success - judging by this showing - still looks steep.
Ricky Hatton Memorial Motivates All-Manchester Fight
In the co-main event, Arthur defeated Rea by divided decision in a excellent all-Manchester contest to win the European light-heavyweight belt.
The venue became quiet for a profoundly moving memorial before the fight as 10 bells sounded in honor of Manchester's own Ricky Hatton, who passed away aged 46 in September.
It was the initial significant broadcast fight night in the location since Hatton's passing. As the final chime ended, the stillness transitioned to a roar of "there's only one Ricky Hatton".
The fighting inside the ropes equaled the feeling. The eventual winner was sent to the canvas by a significant blow squarely on the face in the early round, getting up unsteadily to his feet on the count of eight.
But the traditional red shorts of the fighter soon came forward again. Across the ring, Rea - in opposing blue - was marked up early, noticeable damage developing under his eye as the fighters traded hard punches.
Rea, 27, landed power punches but Arthur, 34, matched the intensity with effective uppercuts as the pace hardly diminished over twelve rounds.
Arthur narrowly won the result with scoring tallies of even score, 115-113 and clearer margin, but both fighters were determined and full of heart, exactly what their hero the legend represented.
