UK light-heavyweight Buatsi secured a victory yet unimpressive start to his career under new promoters with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's activity level likely gained him a judges' verdict in a tight ten-round contest at the Manchester venue.
But the challenger had his moments, landing some telling clean blows in a contest where the styles never quite clicked, with excessive holding disrupting the action.
The scoring judges scored it 96-94 to the winner, with the final judge a even score.
"It wasn't my greatest performance but what do champions do? They prevail," Buatsi stated in the arena as he was met by negative reactions from the spectators.
The Londoner returned to winning ways after his first professional defeat - an epic battle with his previous opponent in last winter - to earn a twentieth professional win.
Some ringside observers thought Parker, 31, merited the win but the British boxer suffered the second setback of his 28-bout professional journey.
The Champion Claims Triumph in Dull Affair
His career development has slowed in recent times through contract problems and long spells of inactivity.
Previously predicted as the future of British boxing, he now finds himself trying to achieve expectations - possibly in what seems like a last chance - under recent support.
He started carefully, with both competitors prepared to overcommit in a calculated 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 competing in only his second fight at light heavyweight.
By the fight's midpoint, Parker had stayed in contention, causing problems for Buatsi, who utilized a tight guard to narrowly win the better rounds.
The audience's tolerance wore thin during regular grabbing, with the challenger falling to the floor several times during close exchanges.
The underdog ended stronger, but multiple periods were hard to judge. Nevertheless, ex-champion the boxing analyst - working with Dazn - had it particularly wide for the challenger, scoring for Buatsi just only one stanza.
The victor progresses, but with the likes of power puncher David Benavidez, and Russian star Bivol leading the category, the journey to titles - on this evidence - still appears challenging.
Hatton Memorial Inspires All-Manchester Fight
In the supporting bout, Lyndon Arthur defeated Bradley Rea by divided decision in a terrific all-Manchester fight to capture the continental belt.
The stadium fell silent for a profoundly moving homage ahead of the contest as ten bells tolled in remembrance of Manchester's own Hatton, who succumbed 46 years old in September.
It was the premier televised fight night in the location since the passing of Hatton. As the last bell ended, the stillness transitioned to a roar of "there's only one Hatton".
The fighting during the bout reflected the sentiment. The eventual winner was sent to the canvas by a left hook squarely on the face in the second round, getting up unsteadily to his feet on the referee's count.
But the Manchester United-red equipment of Arthur soon pressed ahead again. From the other corner, Rea - in rival City blue - was injured quickly, noticeable damage forming under his eye as the duo landed hard punches.
Rea, 27, connected with strong blows but the champion, 34, fought fire with fire with stinging uppercuts as the action rarely dropped over 12 rounds.
The victor barely secured the result with judges scorecards of 114-114, narrow lead and clearer margin, but each competitor were determined and courageous, all the qualities their idol the legend represented.
