UK light heavyweight Buatsi earned a win yet unimpressive start to his career under new promoters with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level appeared to earn him a judges' verdict in a tight 10-round contest at the boxing arena.
But Parker landed significant shots, landing some telling individual punches in a match where the styles didn't complement each other, with frequent clinching spoiling the action.
Two judges judged it 96-94 to Buatsi, with the third a 95-95 draw.
"It wasn't my finest performance but how do champions respond? They succeed," the victor commented in the arena as he was met by negative reactions from the crowd.
The British fighter returned to winning ways after his first professional defeat - an epic battle with his previous opponent in February - to secure a 20th career victory.
Some ringside observers believed Parker, 31, should have been awarded the decision but the contender endured the second setback of his 28-match career.
Buatsi Secures Triumph in Slow Encounter
The fighter's advancement has slowed in recent years through management issues and long spells of inactivity.
Earlier forecast as the next star of UK boxing, he now finds himself trying to realize his potential - perhaps in what seems like a ultimate opportunity - under fresh management.
He began cautiously, with both competitors willing to take risks in a cagey initial rounds.
Parker, whose sole prior loss came at the lower weight class against his former opponent in two years ago after breaking his hand during the bout, was participating in his second appearance at light-heavyweight.
By the middle rounds, the underdog had stayed in contention, causing problems for the favorite, who worked behind a protective stance to edge the more effective rounds.
The crowd's patience wore thin during frequent holding, with the challenger going down several times during clinches.
Parker finished the stronger, but many rounds were hard to judge. However, previous titleholder Carl Frampton - working with the broadcast network - had it significantly in favor for the challenger, giving Buatsi just a single round.
The victor moves on, but with the likes of power puncher Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the road to world glory - on this evidence - still looks steep.
Hatton Memorial Fuels All-Manchester Battle
In the secondary fight, Arthur overcame Rea by close verdict in a outstanding all-Manchester fight to win the continental championship.
The arena fell silent for a deeply poignant homage prior to the bout as ten bells tolled in memory of local hero Ricky Hatton, who died aged 46 in September.
It was the premier televised boxing event in the location since Hatton's passing. As the last bell disappeared, the stillness gave way to a roar of "only one Hatton".
The fighting during the bout matched the emotion. The eventual winner was floored by a powerful punch flush on the face in the initial stage, getting up unsteadily to his footing on the referee's count.
But the traditional red equipment of Arthur soon advanced again. On the opposite side, Rea - in opposing blue - was injured quickly, significant bruising developing under his face as the pair landed punishing blows.
Rea, 27, delivered effective strikes but Arthur, 34, matched the intensity with powerful upward punches as the pace rarely dropped over twelve rounds.
The victor edged the result with official scores of draw, close margin and clearer margin, but both fighters were persistent and courageous, exactly what their hero Hatton stood for.
