UK light-heavyweight Buatsi secured a victory yet disappointing beginning to his career under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's activity level likely gained him a split decision in a close 10-round bout at the Co-op Live Arena.
But the challenger had his moments, landing some telling individual punches in a match where the techniques never quite clicked, with constant grabbing spoiling the fight.
Two judges had it 96-94 in favor to the winner, with the third a 95-95 draw.
"It wasn't my finest showing but what do champions do? They prevail," Buatsi stated in the arena as he was greeted with boos 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.
Some ringside observers thought Parker, 31, merited the victory but the Derbyshire fighter experienced the second setback of his 28-bout career.
Buatsi Secures Triumph in Uneventful Affair
The fighter's advancement has slowed in recent times through contract problems and extended periods of inactivity.
Previously predicted as the next star of British boxing, he now stands trying to fulfil that early promise - perhaps in what appears to be a ultimate opportunity - under fresh management.
He opened tentatively, with both competitors ready to be aggressive in a calculated early stages.
Parker, whose sole prior loss came at super middleweight against John Ryder in 2022 after suffering a hand injury mid-fight, was participating in his second appearance at light-heavyweight.
By the middle rounds, Parker had stayed in contention, making life awkward for Buatsi, who utilized a solid defense to edge the more effective rounds.
The crowd's patience wore thin during regular grabbing, with Parker going down multiple occasions during clinches.
Parker closed well, but several stanzas were challenging to assess. However, ex-champion Carl Frampton - working with Dazn - had it significantly in favor for the challenger, awarding Buatsi just only one stanza.
The victor progresses, but with the caliber of hard hitter David Benavidez, and Russian star Bivol dominating the weight class, the journey to titles - judging by this showing - still appears challenging.
Hatton Memorial Motivates All-Manchester Battle
In the supporting bout, Arthur overcame Rea by divided decision in a excellent local rivalry contest to capture the continental belt.
The stadium grew hushed for a deeply poignant memorial ahead of the contest as 10 bells rang in memory of Manchester's own Hatton, who passed away at age 46 in September.
It was the premier televised boxing event in the city since Hatton's passing. As the concluding sound disappeared, the silence gave way to a chant of "there's only one Ricky Hatton".
The action during the bout matched the emotion. The eventual winner was floored by a powerful punch directly to the face in the early round, standing uncertainly to his feet on the count of eight.
But the Manchester United-red equipment of Arthur soon advanced again. Across the ring, the opponent - in rival City blue - was marked up soon, significant bruising developing under his orbital area as the pair exchanged powerful shots.
The challenger, 27, connected with strong blows but the champion, 34, matched the intensity with stinging uppercuts as the intensity hardly diminished over the full distance.
The victor barely secured the verdict with scoring tallies of 114-114, 115-113 and wider gap, but both fighters were relentless and full of heart, all the qualities their inspiration the legend stood for.
