British light-heavyweight Buatsi earned a win yet unimpressive start to life under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's work rate likely gained him a judges' verdict in a tight ten-round fight at the boxing arena.
But the challenger found success, connecting with powerful clean blows in a fight where the techniques failed to mesh, with excessive holding marring the action.
The scoring judges judged it 96-94 to the winner, with the remaining official a even score.
"It wasn't my finest display but what do champions do? They succeed," Buatsi commented in the ringside as he was faced boos from the crowd.
The British fighter returned to winning ways after his first professional defeat - an thrilling contest with his previous opponent in last winter - to earn a twentieth professional win.
Several boxing experts thought the challenger, 31, should have been awarded the win but the contender suffered the second setback of his 28-fight career.
The Champion Earns Victory in Slow Affair
The fighter's advancement has slowed in recent years through promotional disputes and considerable time of lack of fights.
Earlier forecast as the next star of the British fight scene, he now is positioned trying to realize his potential - possibly in what feels like a ultimate opportunity - under recent support.
He began cautiously, with the two boxers ready to be aggressive in a calculated early stages.
The challenger, whose single earlier setback came at super middleweight against John Ryder in two years ago after damaging his hand mid-fight, was competing in only his second fight at light heavyweight.
By the middle rounds, Parker had kept it close, creating difficulties for Buatsi, who utilized a tight guard to barely take the more effective periods.
The crowd's patience wore thin amid regular grabbing, with Parker going down several times during grappling.
Parker ended stronger, but several stanzas were hard to judge. However, former world champion Carl Frampton - working with the broadcast network - had it particularly wide for Parker, scoring for Buatsi just only one stanza.
Buatsi progresses, but with the presence of hard hitter Benavidez, and Russian champion Bivol dominating the weight class, the journey to titles - judging by this showing - still looks steep.
Ricky Hatton Tribute Inspires Manchester Derby Fight
In the secondary fight, Lyndon Arthur defeated Bradley Rea by split-decision in a excellent all-Manchester contest to capture the European light heavyweight championship.
The arena fell silent for a profoundly moving homage prior to the bout as ten bells sounded in remembrance of the city's native Ricky Hatton, who succumbed 46 years old in September.
It was the first major televised fight night in the city since the passing of Hatton. As the final chime faded, the quiet became a roar of "only one Hatton".
The action during the bout matched the emotion. Arthur was knocked down by a powerful punch flush on the chin in the initial stage, getting up unsteadily to his footing on the count of eight.
But the red-colored attire of the fighter soon came forward again. On the opposite side, the opponent - in opposing blue - was injured quickly, significant bruising forming under his orbital area as the duo exchanged punishing blows.
Rea, 27, delivered effective strikes but the champion, 34, responded in kind with effective uppercuts as the pace rarely dropped over twelve rounds.
Arthur edged the verdict with judges scorecards of even score, 115-113 and 115-112, but both fighters were persistent and courageous, exactly what their hero the legend embodied.
