UK light-heavyweight Buatsi made a winning yet underwhelming start to his career under new promoters with a points victory over Zach Parker in Manchester.
The Olympic medal winner's work rate likely gained him a majority decision in a competitive ten-round fight at the Co-op Live Arena.
But Parker found success, delivering effective single shots in a match where the approaches never quite clicked, with excessive holding marring the fight.
Two judges scored it 96-94 in favor to Buatsi, with the third a 95-95.
"It wasn't my finest performance but how do champions respond? They win," the victor stated in the arena as he was greeted with boos from the audience.
The British fighter got back to winning after his maiden career setback - an epic battle with his previous opponent in last winter - to secure a 20th pro success.
Several boxing experts believed the challenger, thirty-one, deserved the victory but the British boxer experienced the second setback of his 28-fight career.
Buatsi Claims Victory in Uneventful Affair
The fighter's advancement has slowed in the past few years through contract problems and considerable time of inactivity.
Once tipped as the next star of British boxing, he now stands trying to realize his potential - possibly in what feels like a last chance - under recent support.
He opened tentatively, with neither fighter ready to overcommit in a tentative opening few rounds.
The challenger, whose single earlier setback came at super-middleweight against his former opponent in two years ago after damaging his hand during the bout, was participating in his second appearance at light-heavyweight.
By the middle rounds, Parker had kept it close, creating difficulties for Buatsi, who utilized a protective stance to narrowly win the more effective periods.
The crowd's patience diminished because of constant clinching, with Parker going down multiple occasions during grappling.
Parker closed well, but several stanzas were difficult to score. Although, former world champion Carl Frampton - commentating on Dazn - had it strongly leaning for the challenger, awarding Buatsi just one round.
Buatsi progresses, but with the likes of power puncher Benavidez, and Eastern European fighter Bivol ruling the division, the road to world glory - on this evidence - still appears challenging.
Hatton Tribute Fuels Local Rivalry Battle
In the co-main event, Arthur beat Rea by split-decision in a terrific local rivalry fight to win the European light-heavyweight championship.
The venue grew hushed for a deeply poignant memorial before the fight as 10 bells rang in memory of the city's native Ricky Hatton, who passed away aged 46 in September.
It was the premier televised boxing event in the urban center since Hatton's passing. As the last bell faded, the stillness gave way to a roar of "only one Ricky Hatton".
The competition within the ring reflected the sentiment. Arthur was knocked down by a significant blow flush on the chin in the early round, getting up unsteadily to his position on the eight count.
But the traditional red attire of the fighter soon advanced again. Across the ring, the opponent - in opposing blue - was injured quickly, heavy swelling appearing under his eye as the duo landed powerful shots.
The challenger, 27, landed power punches but the champion, 34, fought fire with fire with stinging uppercuts as the pace rarely dropped over 12 rounds.
The victor narrowly won the result with scoring tallies of even score, narrow lead and 115-112, but both fighters were persistent and full of heart, all the qualities their idol the legend embodied.
