British light heavyweight Buatsi secured a victory yet unimpressive start to his career under new promoters with a decision win over Zach Parker in Manchester.
The Olympic medal winner's punch output appeared to earn him a judges' verdict in a close ten-round fight at the boxing arena.
But Parker found success, connecting with powerful clean blows in a fight where the techniques never quite clicked, with excessive holding disrupting the fight.
The scoring judges scored it 96-94 to Buatsi, with the third a 95-95 draw.
"It wasn't my greatest showing but what defines champions? They succeed," Buatsi commented in the arena as he was faced negative reactions from the audience.
The Londoner bounced back after his initial pro loss - an thrilling contest with Callum Smith in last winter - to secure a 20th career victory.
Several boxing experts believed Parker, thirty-one, should have been awarded the victory but the contender suffered the second loss of his 28-bout professional journey.
Buatsi Earns Triumph in Dull Affair
The fighter's advancement has plateaued in the past few years through management issues and extended periods of inactivity.
Previously predicted as the rising talent of the British fight scene, he now stands trying to fulfil that early promise - maybe in what feels like a last chance - under new promotional backing.
He started carefully, with both competitors ready to take risks in a tentative initial rounds.
Parker, whose only previous defeat came at the lower weight class against John Ryder in 2022 after suffering a hand injury during the bout, was participating in his second appearance at the higher weight class.
By the middle rounds, the underdog had stayed in contention, making life awkward for Buatsi, who operated with a solid defense to edge the cleaner stanzas.
The crowd's patience wore thin because of frequent holding, with the challenger going down multiple occasions during grappling.
The underdog finished the stronger, but many rounds were hard to judge. Although, ex-champion Carl Frampton - commentating on Dazn - had it strongly leaning for the challenger, scoring for Buatsi just only one stanza.
Buatsi progresses, but with the caliber of power puncher Benavidez, and Russian champion Dmitry Bivol leading the category, the journey to titles - on this evidence - still seems difficult.
Hatton Homage Fuels Local Rivalry Fight
In the secondary fight, Arthur defeated Rea by split-decision in a outstanding local rivalry fight to capture the continental title.
The venue became quiet for a deeply poignant homage ahead of the contest as ten bells sounded in memory of local hero Hatton, who succumbed 46 years old in recently.
It was the premier televised boxing event in the city since the passing of Hatton. As the concluding sound ended, the stillness transitioned to a chant of "there's only one Hatton".
The action within the ring reflected the emotion. The eventual winner was knocked down by a left hook directly to the face in the second round, getting up unsteadily to his footing on the eight count.
But the traditional red equipment of the fighter soon advanced again. On the opposite side, the opponent - in competitive blue - was marked up quickly, heavy swelling forming under his face as the duo traded hard punches.
Rea, 27, connected with strong blows but the champion, 34, responded in kind with powerful upward punches as the pace hardly diminished over 12 rounds.
The victor edged the decision with scoring tallies of 114-114, close margin and 115-112, but each competitor were persistent and full of heart, everything their inspiration the legend embodied.
