British light heavyweight Buatsi made a winning yet underwhelming beginning to his career under fresh promotional backing with a unanimous decision 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 Manchester venue.
But the challenger landed significant shots, landing some telling single shots in a fight where the approaches didn't complement each other, with frequent clinching spoiling the action.
The scoring judges scored it 96-94 in favor to the winner, with the third a 95-95 draw.
"It wasn't my greatest performance but what do champions do? They prevail," the victor stated in the ring as he was faced negative reactions from the crowd.
The Londoner returned to winning ways after his initial pro loss - an memorable fight with his previous opponent in last winter - to earn a 20th pro success.
Some ringside observers thought Parker, 31, should have been awarded the win but the British boxer experienced the second defeat of his 28-bout professional journey.
The Champion Claims Win in Uneventful Encounter
His career development has stalled in the past few years through contract problems and extended periods of inactivity.
Earlier forecast as the rising talent of UK boxing, he now finds himself trying to fulfil that early promise - perhaps in what feels like a last chance - under recent support.
He began cautiously, with the two boxers willing to take risks in a calculated opening few rounds.
Parker, whose single earlier setback came at super middleweight against John Ryder in two years ago after damaging his hand during the bout, was competing in only his second fight at light heavyweight.
By the halfway stage, the underdog had made it competitive, creating difficulties for the favorite, who operated with a solid defense to narrowly win the better periods.
The spectators' acceptance decreased amid constant clinching, with Parker falling to the floor multiple occasions during clinches.
The underdog finished the stronger, but multiple periods were hard to judge. Nevertheless, previous titleholder Carl Frampton - working with Dazn - had it strongly leaning for Parker, scoring for Buatsi just a single round.
The victor progresses, but with the likes of heavy hitter Benavidez, and Russian star Dmitry Bivol leading the category, the journey to titles - on this evidence - still looks steep.
Ricky Hatton Memorial Inspires All-Manchester Battle
In the co-main event, Lyndon Arthur overcame Rea by close verdict in a excellent local rivalry fight to secure the European light heavyweight championship.
The arena fell silent for a deeply poignant tribute ahead of the contest as ten bells sounded in memory of local hero Hatton, who succumbed at age 46 in recently.
It was the initial significant broadcast match card in the location since the passing of Hatton. As the last bell disappeared, the silence transitioned to a roar of "only one Ricky Hatton".
The action within the ring matched the sentiment. Arthur was floored by a powerful punch directly to the face in the initial stage, standing uncertainly to his position on the eight count.
But the traditional red attire of Arthur soon came forward again. On the opposite side, Rea - in opposing blue - was injured quickly, heavy swelling appearing under his orbital area as the pair exchanged powerful shots.
The challenger, twenty-seven, connected with strong blows but Arthur, thirty-four, matched the intensity with powerful upward punches as the intensity seldom decreased over 12 rounds.
Arthur narrowly won the verdict with scoring tallies of draw, narrow lead and clearer margin, but the two athletes were persistent and full of heart, exactly what their idol Hatton embodied.
