UK light heavyweight Buatsi made a winning yet unimpressive beginning to his career under new promoters with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's work rate likely gained him a split decision in a tight 10-round contest at the Manchester venue.
But Parker found success, delivering effective clean blows in a match where the styles never quite clicked, with frequent clinching spoiling the action.
Two judges scored it 96-94 for to the winner, with the remaining official a 95-95 draw.
"It wasn't my greatest performance but what do champions do? They prevail," the victor commented in the arena as he was faced negative reactions from the crowd.
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 twentieth professional win.
Various analysts thought Parker, 31, merited the decision but the British boxer endured the second loss of his 28-match career.
The Champion Secures Win in Dull Match
Buatsi's progress has stalled in recent times through contract problems and long spells of inactivity.
Earlier forecast as the rising talent of British boxing, he now stands trying to achieve expectations - possibly in what seems like a ultimate opportunity - under fresh management.
He started carefully, with both competitors willing to overcommit in a tentative initial rounds.
The challenger, 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 fight's midpoint, the underdog had made it competitive, creating difficulties for Buatsi, who utilized a solid defense to edge the cleaner periods.
The spectators' acceptance diminished during regular grabbing, with the challenger slipping to the canvas several times during grappling.
Parker closed well, but many rounds were hard to judge. However, former world champion Carl Frampton - providing analysis for the broadcast network - had it strongly leaning for the challenger, awarding Buatsi just one round.
Buatsi advances, but with the presence of heavy hitter David Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the road to world glory - on this evidence - still looks steep.
Hatton Memorial Fuels Local Rivalry Contest
In the secondary fight, Arthur beat Bradley Rea by split-decision in a terrific local rivalry fight to win the European light heavyweight belt.
The venue grew hushed for a extremely emotional homage before the fight as a bell ceremony tolled in remembrance of Manchester's own Hatton, who succumbed at age 46 in September.
It was the first major televised boxing event in the location since Hatton's passing. As the final chime ended, the silence became a shout of "there's just one Ricky Hatton".
The competition inside the ropes equaled the feeling. The eventual winner was sent to the canvas by a significant blow flush on the chin in the early round, getting up unsteadily to his feet on the referee's count.
But the traditional red equipment of Arthur soon advanced again. Across the ring, Rea - in opposing blue - was marked up quickly, significant bruising forming under his eye as the fighters exchanged powerful shots.
The challenger, twenty-seven, connected with strong blows but Arthur, thirty-four, matched the intensity with stinging uppercuts as the pace hardly diminished over the full distance.
Arthur barely secured the decision with judges scorecards of draw, 115-113 and clearer margin, but the two athletes were determined and brave, exactly what their hero Hatton stood for.
