British light heavyweight Buatsi earned a win yet disappointing start to his career under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's work rate likely gained him a split decision in a competitive 10-round fight at the Co-op Live Arena.
But Parker landed significant shots, delivering effective single shots in a contest where the styles didn't complement each other, with constant grabbing marring the action.
Two judges scored it 96-94 in favor to the winner, with the third a even score.
"It wasn't my finest performance but what do champions do? They win," the victor stated in the ringside as he was met by negative reactions from the audience.
The British fighter returned to winning ways after his initial pro loss - an epic battle with his previous opponent in last winter - to secure a twentieth professional win.
Various analysts believed the challenger, 31, deserved the win but the British boxer experienced the second defeat of his 28-match professional journey.
Buatsi Earns Win in Dull Affair
The fighter's advancement has plateaued in recent years through contract problems and considerable time of lack of fights.
Previously predicted as the next star of British boxing, he now finds himself trying to fulfil that early promise - perhaps in what seems like a ultimate opportunity - under recent support.
He started carefully, with both competitors ready to be aggressive in a tentative initial rounds.
The challenger, whose sole prior loss came at the lower weight class against John Ryder in two years ago after suffering a hand injury in the contest, was making just his second bout at light heavyweight.
By the halfway stage, Parker had kept it close, making life awkward for Buatsi, who operated with a protective stance to narrowly win the better stanzas.
The crowd's patience decreased because of regular grabbing, with Parker falling to the floor various instances during close exchanges.
The underdog closed well, but multiple periods were challenging to assess. Nevertheless, previous titleholder the boxing analyst - working with Dazn - had it particularly wide for the challenger, scoring for Buatsi just a single round.
Buatsi progresses, but with the caliber of power puncher David Benavidez, and Russian champion Bivol ruling the division, the road to world glory - on this evidence - still looks steep.
Hatton Homage Inspires Manchester Derby Contest
In the secondary fight, Lyndon Arthur defeated Bradley Rea by split-decision in a excellent all-Manchester battle to capture the continental title.
The venue grew hushed for a extremely emotional memorial prior to the bout as ten bells rang in remembrance of the city's native Hatton, who succumbed at age 46 in last month.
It was the initial significant broadcast match card in the location since the passing of Hatton. As the concluding sound faded, the quiet gave way to a roar of "there's just one Hatton".
The competition inside the ropes reflected the sentiment. Arthur was floored by a significant blow squarely on the chin in the second round, standing uncertainly to his feet on the count of eight.
But the red-colored shorts of Arthur soon came forward again. On the opposite side, Rea - in competitive blue - was marked up soon, noticeable damage forming under his eye as the fighters traded powerful shots.
Rea, 27, delivered effective strikes but the champion, 34, responded in kind with powerful upward punches as the action seldom decreased over 12 rounds.
Arthur edged the decision with judges scorecards of 114-114, narrow lead and wider gap, but each competitor were relentless and full of heart, all the qualities their inspiration Hatton stood for.
