UK light heavyweight Buatsi earned a win yet unimpressive beginning to life under new promoters with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's punch output likely gained him a judges' verdict in a close ten-round fight at the boxing arena.
But the challenger landed significant shots, delivering effective individual punches in a contest where the techniques didn't complement each other, with excessive holding marring the contest.
The officials had it 96-94 for to Buatsi, with the remaining official a 95-95.
"It wasn't my greatest display but what do champions do? They succeed," the victor stated in the ring as he was faced negative reactions from the spectators.
The Londoner returned to winning ways after his initial pro loss - an epic battle with Callum Smith in February - to secure a 20th pro success.
Some ringside observers felt the challenger, 31, deserved the win but the Derbyshire fighter endured the second loss of his 28-match career.
The Champion Earns Triumph in Uneventful Encounter
Buatsi's progress has slowed in recent years through promotional disputes and long spells of inactivity.
Once tipped as the next star of British boxing, he now is positioned trying to fulfil that early promise - maybe in what appears to be a last chance - under new promotional backing.
He began cautiously, with both competitors ready to overcommit in a cagey early stages.
Parker, whose sole prior loss came at the lower weight class against John Ryder in two years ago after damaging his hand in the contest, was competing in only his second fight at the higher weight class.
By the halfway stage, Parker had stayed in contention, creating difficulties for the favorite, who operated with a protective stance to narrowly win the cleaner rounds.
The spectators' acceptance decreased amid frequent holding, with the challenger falling to the floor multiple occasions during close exchanges.
The underdog ended stronger, but multiple periods were challenging to assess. Nevertheless, previous titleholder Carl Frampton - providing analysis for Dazn - had it particularly wide for the challenger, scoring for Buatsi just one round.
Buatsi advances, but with the presence of heavy hitter David Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the road to world glory - judging by this showing - still appears challenging.
Hatton Tribute Motivates Manchester Derby Contest
In the co-main event, Lyndon Arthur beat Bradley Rea by split-decision in a outstanding all-Manchester contest to win the European light heavyweight title.
The arena became quiet for a deeply poignant tribute ahead of the contest as a bell ceremony tolled in remembrance of Manchester's own Ricky Hatton, who passed away at age 46 in last month.
It was the initial significant broadcast fight night in the city since the passing of Hatton. As the concluding sound disappeared, the stillness became a chant of "there's just one Ricky Hatton".
The fighting within the ring reflected the sentiment. The eventual winner was floored by a significant blow squarely on the face in the early round, rising shakily to his position on the referee's count.
But the traditional red equipment of the fighter soon came forward again. On the opposite side, the opponent - in rival City blue - was damaged early, heavy swelling developing under his orbital area as the pair exchanged punishing blows.
Rea, twenty-seven, landed power punches but the champion, 34, matched the intensity with effective uppercuts as the intensity rarely dropped over twelve rounds.
Arthur edged the verdict with official scores of even score, 115-113 and wider gap, but each competitor were determined and brave, everything their hero the legend embodied.
