UK light heavyweight Buatsi made a winning yet disappointing debut to his career under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic medal winner's activity level likely gained him a majority decision in a competitive 10-round contest at the Manchester venue.
But Parker landed significant shots, landing some telling clean blows in a contest where the styles failed to mesh, with excessive holding spoiling the fight.
Two judges scored it 96-94 in favor to the winner, with the remaining official a even score.
"It wasn't my best performance but what defines champions? They succeed," Buatsi said in the arena as he was met by disapproval from the spectators.
The Londoner got back to winning after his first professional defeat - an epic battle with his previous opponent in February - to claim a twentieth professional win.
Various analysts believed Parker, 31, deserved the win but the British boxer experienced the second loss of his 28-match career.
Buatsi Earns Victory in Dull Affair
His career development has slowed in recent years through contract problems and considerable time of inactivity.
Earlier forecast as the rising talent of UK boxing, he now is positioned trying to achieve expectations - possibly in what feels like a final roll of the dice - under recent support.
He started carefully, with the two boxers willing to be aggressive in a calculated initial rounds.
Parker, whose only previous defeat came at super middleweight against John Ryder in two years ago after suffering a hand injury during the bout, was participating in his second bout at light heavyweight.
By the middle rounds, the underdog had kept it close, causing problems for Buatsi, who worked behind a protective stance to edge the more effective periods.
The spectators' acceptance decreased because of constant clinching, with Parker falling to the floor multiple occasions during close exchanges.
The underdog ended stronger, but several stanzas were hard to judge. However, ex-champion Carl Frampton - commentating on the broadcast network - had it strongly leaning for the challenger, awarding Buatsi just one round.
The victor advances, but with the caliber of hard hitter David Benavidez, and Russian star Bivol ruling the division, the path to championship success - judging by this showing - still appears challenging.
Ricky Hatton Memorial Fuels Manchester Derby Battle
In the supporting bout, Lyndon Arthur overcame Rea by divided decision in a excellent local rivalry battle to capture the European light-heavyweight title.
The stadium fell silent for a profoundly moving memorial prior to the bout as ten bells rang in remembrance of Manchester's own Hatton, who succumbed 46 years old in recently.
It was the initial significant broadcast fight night in the urban center since Hatton's death. As the final chime disappeared, the quiet transitioned to a chant of "there's just one Hatton".
The action during the bout matched the feeling. The eventual winner was sent to the canvas by a significant blow squarely on the jaw in the initial stage, getting up unsteadily to his position on the eight count.
But the red-colored shorts of Arthur soon advanced again. On the opposite side, Rea - in competitive blue - was damaged soon, significant bruising developing under his face as the duo traded punishing blows.
Rea, 27, delivered effective strikes but Arthur, 34, responded in kind with effective uppercuts as the intensity rarely dropped over the full distance.
The victor barely secured the decision with scoring tallies of even score, 115-113 and clearer margin, but the two athletes were determined and courageous, all the qualities their idol the legend stood for.
