UK light heavyweight Buatsi secured a victory yet unimpressive beginning to his career under fresh promotional backing with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's punch output likely gained him a split decision in a competitive ten-round fight at the Co-op Live Arena.
But Parker had his moments, landing some telling individual punches in a contest where the techniques didn't complement each other, with excessive holding disrupting the action.
The scoring judges had it 96-94 in favor to the winner, with the final judge a 95-95.
"It wasn't my greatest showing but what do champions do? They succeed," the victor said in the arena as he was greeted with boos from the crowd.
The British fighter got back to winning after his maiden career setback - an epic battle with Callum Smith in February - to claim a twentieth professional win.
Various analysts felt Parker, thirty-one, should have been awarded the victory but the contender experienced the second defeat of his 28-bout career.
The Champion Secures Victory in Dull Match
Buatsi's progress has stalled in recent times through management issues and considerable time of lack of fights.
Previously predicted as the future of the British fight scene, he now is positioned trying to achieve expectations - possibly in what feels like a last chance - under new promotional backing.
He started carefully, with the two boxers willing to take risks in a tentative initial rounds.
Parker, whose single earlier setback came at super-middleweight against his former opponent in two years ago after breaking his hand in the contest, was competing in only his second bout at the higher weight class.
By the halfway stage, Parker had made it competitive, creating difficulties for the favorite, who worked behind a protective stance to barely take the more effective stanzas.
The spectators' acceptance diminished amid frequent holding, with Parker falling to the floor multiple occasions during grappling.
The underdog finished the stronger, but several stanzas were hard to judge. Nevertheless, previous titleholder the boxing analyst - commentating on Dazn - had it strongly leaning for Parker, awarding Buatsi just a single round.
The victor progresses, but with the presence of heavy hitter Benavidez, and Russian star Bivol leading the category, the journey to titles - judging by this showing - still looks steep.
Ricky Hatton Homage Inspires Local Rivalry Battle
In the co-main event, Arthur defeated Rea by split-decision in a terrific Manchester vs Manchester contest to secure the continental belt.
The venue fell silent for a profoundly moving tribute ahead of the contest as 10 bells tolled in remembrance of Manchester's own Ricky Hatton, who passed away at age 46 in recently.
It was the initial significant broadcast fight night in the location since the passing of Hatton. As the final chime ended, the stillness transitioned to a chant of "only one Hatton".
The action inside the ropes matched the feeling. The eventual winner was knocked down by a significant blow flush on the face in the initial stage, standing uncertainly to his position on the count of eight.
But the Manchester United-red shorts of the fighter soon advanced again. On the opposite side, the opponent - in competitive blue - was injured quickly, significant bruising forming under his eye as the fighters traded powerful shots.
The challenger, twenty-seven, landed power punches but Arthur, 34, responded in kind with effective uppercuts as the action rarely dropped over twelve rounds.
Arthur edged the verdict with scoring tallies of even score, narrow lead and wider gap, but both fighters were relentless and brave, all the qualities their inspiration Hatton represented.
