UK light-heavyweight Buatsi secured a victory yet unimpressive debut to his career under fresh promotional backing with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's activity level likely gained him a majority decision in a tight 10-round fight at the boxing arena.
But Parker landed significant shots, connecting with powerful single shots in a match where the styles failed to mesh, with constant grabbing marring the contest.
The scoring judges scored it 96-94 for to Buatsi, with the third a even score.
"It wasn't my finest showing but how do champions respond? They win," the victor commented in the ringside as he was greeted with disapproval from the spectators.
The British fighter returned to winning ways after his initial pro loss - an thrilling contest with Callum Smith in February - to secure a twentieth professional win.
Various analysts believed the challenger, 31, should have been awarded the decision but the Derbyshire fighter endured the second loss of his 28-bout career.
Buatsi Secures Victory in Dull Affair
Buatsi's progress has stalled in recent times through contract problems and long spells of inactivity.
Earlier forecast as the next star of UK boxing, he now stands trying to fulfil that early promise - perhaps in what appears to be a final roll of the dice - under new promotional backing.
He began cautiously, with the two boxers prepared to take risks in a cagey initial rounds.
The challenger, whose only previous defeat came at the lower weight class against John Ryder in 2022 after breaking his hand in the contest, 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 the favorite, who worked behind a protective stance to barely take the more effective stanzas.
The spectators' acceptance diminished amid frequent holding, with the challenger falling to the floor various instances during clinches.
Parker ended stronger, but several stanzas were hard to judge. However, ex-champion Carl Frampton - providing analysis for Dazn - had it strongly leaning for the challenger, giving Buatsi just a single round.
Buatsi progresses, but with the likes of heavy hitter Benavidez, and Eastern European fighter Bivol ruling the division, the path to championship success - judging by this showing - still appears challenging.
Hatton Memorial Motivates All-Manchester Contest
In the secondary fight, Arthur beat Bradley Rea by close verdict in a outstanding all-Manchester fight to capture the European light heavyweight championship.
The arena became quiet for a deeply poignant memorial prior to the bout as 10 bells sounded in remembrance of the city's native Ricky Hatton, who passed away 46 years old in recently.
It was the initial significant broadcast match card in the urban center since Hatton's passing. As the final chime disappeared, the stillness gave way to a shout of "there's just one Ricky Hatton".
The competition within the ring matched the feeling. The eventual winner was floored by a powerful punch directly to the jaw in the initial stage, rising shakily to his footing on the count of eight.
But the red-colored shorts of Arthur soon pressed ahead again. Across the ring, the opponent - in competitive blue - was damaged soon, significant bruising forming under his face as the duo landed hard punches.
Rea, twenty-seven, landed power punches but the champion, thirty-four, responded in kind with powerful upward punches as the pace seldom decreased over 12 rounds.
The victor edged the decision with scoring tallies of draw, 115-113 and clearer margin, but both fighters were determined and courageous, everything their hero Hatton stood for.
