British light heavyweight Buatsi made a winning yet unimpressive beginning to his career under fresh promotional backing with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's punch output seemingly secured him a majority decision in a close 10-round bout at the Manchester venue.
But Parker found success, landing some telling single shots in a fight where the styles failed to mesh, with constant grabbing marring the contest.
Two judges scored it 96-94 in favor to Buatsi, with the third a 95-95.
"It wasn't my best display but how do champions respond? They win," the victor commented in the ringside as he was faced negative reactions from the audience.
The British fighter got back to winning after his initial pro loss - an thrilling contest with his previous opponent in February - to claim a twentieth professional win.
Several boxing experts believed Parker, 31, merited the victory but the contender suffered the second setback of his 28-fight career.
Buatsi Earns Victory in Slow Match
The fighter's advancement has slowed in recent times through contract problems and long spells of inactivity.
Previously predicted as the rising talent of British boxing, he now is positioned trying to realize his potential - perhaps in what feels like a final roll of the dice - under fresh management.
He began cautiously, with the two boxers prepared to be aggressive in a cagey opening few rounds.
Parker, whose single earlier setback came at super-middleweight against his former opponent in 2022 after breaking his hand mid-fight, was participating in his second fight at light-heavyweight.
By the halfway stage, Parker had made it competitive, creating difficulties for Buatsi, who operated with a protective stance to narrowly win the better periods.
The crowd's patience decreased amid constant clinching, with the challenger going down multiple occasions during grappling.
The underdog ended stronger, but many rounds were difficult to score. Although, previous titleholder Carl Frampton - working with the broadcast network - had it particularly wide for the challenger, giving Buatsi just only one stanza.
Buatsi moves on, but with the caliber of power puncher Benavidez, and Russian champion Dmitry Bivol ruling the division, the road to world glory - judging by this showing - still looks steep.
Hatton Homage Fuels Local Rivalry Contest
In the secondary fight, Arthur beat Bradley Rea by close verdict in a excellent all-Manchester contest to capture the continental belt.
The arena fell silent for a deeply poignant homage ahead of the contest as 10 bells sounded in memory of Manchester's own Hatton, who succumbed at age 46 in September.
It was the first major televised boxing event in the urban center since Hatton's death. As the final chime ended, the stillness gave way to a shout of "there's just one Ricky Hatton".
The competition within the ring matched the sentiment. Arthur was floored by a left hook flush on the chin in the initial stage, rising shakily to his footing on the eight count.
But the Manchester United-red attire of Arthur soon came forward again. On the opposite side, Rea - in rival City blue - was marked up early, significant bruising developing under his eye as the fighters exchanged hard punches.
Rea, twenty-seven, landed power punches but Arthur, 34, responded in kind with effective uppercuts as the action rarely dropped over 12 rounds.
Arthur narrowly won the result with judges scorecards of even score, narrow lead and clearer margin, but the two athletes were persistent and courageous, exactly what their inspiration the legend stood for.
