UK light-heavyweight Buatsi secured a victory yet unimpressive start to his career under recent management with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's punch output appeared to earn him a split decision in a tight ten-round contest at the boxing arena.
But the challenger landed significant shots, landing some telling single shots in a fight where the styles never quite clicked, with constant grabbing marring the action.
The scoring judges scored it 96-94 in favor to Buatsi, with the remaining official a even score.
"It wasn't my best display but what defines champions? They win," the victor said in the ring as he was faced negative reactions from the crowd.
The Londoner got back to winning after his first professional defeat - an epic battle with Callum Smith in February - to earn a twentieth professional win.
Some ringside observers believed the challenger, 31, deserved the victory but the contender experienced the second loss of his 28-bout career.
Buatsi Secures Win in Dull Encounter
His career development has stalled in the past few years through contract problems and extended periods of inactivity.
Earlier forecast as the next star of the British fight scene, he now is positioned trying to achieve expectations - perhaps in what feels like a ultimate opportunity - under new promotional backing.
He started carefully, with both competitors prepared to take risks in a calculated early stages.
Parker, whose single earlier setback came at super middleweight against John Ryder in two years ago after suffering a hand injury in the contest, was competing in only his second appearance at light-heavyweight.
By the halfway stage, Parker had kept it close, making life awkward for the favorite, who utilized a protective stance to edge the cleaner periods.
The audience's tolerance decreased during constant clinching, with the challenger going down several times during clinches.
Parker finished the stronger, but several stanzas were hard to judge. However, previous titleholder Carl Frampton - commentating on the broadcast network - had it strongly leaning for Parker, scoring for Buatsi just a single round.
Buatsi moves on, but with the presence of power puncher David Benavidez, and Russian champion Dmitry Bivol ruling the division, the road to world glory - judging by this showing - still seems difficult.
Hatton Tribute Inspires All-Manchester Battle
In the co-main event, Lyndon Arthur defeated Bradley Rea by split-decision in a terrific Manchester vs Manchester fight to capture the continental belt.
The stadium grew hushed for a profoundly moving memorial before the fight as a bell ceremony sounded in remembrance of the city's native Ricky Hatton, who succumbed 46 years old in recently.
It was the premier televised match card in the urban center since Hatton's passing. As the final chime ended, the stillness transitioned to a shout of "there's only one Ricky Hatton".
The competition within the ring matched the sentiment. The eventual winner was knocked down by a powerful punch directly to the face in the second round, rising shakily to his feet on the eight count.
But the red-colored attire of Arthur soon advanced again. Across the ring, Rea - in competitive blue - was damaged quickly, significant bruising appearing under his eye as the duo landed punishing blows.
Rea, twenty-seven, connected with strong blows but the champion, thirty-four, matched the intensity with stinging uppercuts as the action hardly diminished over the full distance.
The victor narrowly won the result with judges scorecards of draw, close margin and wider gap, but the two athletes were persistent and brave, all the qualities their idol the legend embodied.
