UK light heavyweight Buatsi secured a victory yet underwhelming beginning 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 majority decision in a tight 10-round contest at the Manchester venue.
But the challenger had his moments, connecting with powerful clean blows in a match where the techniques never quite clicked, with excessive holding disrupting the fight.
Two judges had it 96-94 in favor to Buatsi, with the final judge a even score.
"It wasn't my best showing but what defines champions? They succeed," the victor stated in the ring as he was met by boos 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 secure a 20th pro success.
Some ringside observers thought the challenger, thirty-one, should have been awarded the victory but the contender suffered the second defeat of his 28-fight professional journey.
The Champion Earns Triumph in Uneventful Encounter
The fighter's advancement has slowed in recent times through contract problems and long spells of inactivity.
Earlier forecast as the future of the British fight scene, he now stands trying to achieve expectations - possibly in what seems like a final roll of the dice - under new promotional backing.
He began cautiously, with both competitors willing to take risks in a calculated opening few rounds.
The challenger, whose sole prior loss came at super middleweight against John Ryder in 2022 after suffering a hand injury in the contest, was making just his second fight at the higher weight class.
By the halfway stage, the underdog had kept it close, making life awkward for the favorite, who utilized a solid defense to narrowly win the cleaner periods.
The spectators' acceptance wore thin amid constant clinching, with the challenger falling to the floor various instances during grappling.
The underdog finished the stronger, but several stanzas were challenging to assess. However, previous titleholder Carl Frampton - providing analysis for the broadcast network - had it significantly in favor for the challenger, awarding Buatsi just a single round.
Buatsi advances, but with the caliber of heavy hitter Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the journey to titles - on this evidence - still appears challenging.
Hatton Tribute Inspires All-Manchester Contest
In the supporting bout, Arthur defeated Bradley Rea by divided decision in a terrific all-Manchester fight to capture the European light heavyweight title.
The stadium became quiet for a profoundly moving tribute prior to the bout as ten bells tolled in memory of Manchester's own Ricky Hatton, who passed away 46 years old in recently.
It was the first major televised fight night in the location since the passing of Hatton. As the last bell faded, the quiet gave way to a roar of "only one Ricky Hatton".
The fighting within the ring equaled the feeling. The eventual winner was floored by a powerful punch squarely on the chin in the early round, rising shakily to his position on the count of eight.
But the traditional red shorts of the fighter soon pressed ahead again. On the opposite side, Rea - in competitive blue - was marked up early, heavy swelling forming under his eye as the fighters landed powerful shots.
Rea, twenty-seven, delivered effective strikes but the champion, 34, fought fire with fire with powerful upward punches as the action rarely dropped over 12 rounds.
The victor narrowly won the result with scoring tallies of 114-114, 115-113 and clearer margin, but each competitor were persistent and courageous, everything their idol Hatton embodied.
