British light-heavyweight Buatsi made a winning yet disappointing beginning to his career under new promoters with a decision win over Zach Parker in Manchester.
The Olympic medal winner's work rate seemingly secured him a judges' verdict in a tight 10-round contest at the Manchester venue.
But the challenger had his moments, landing some telling clean blows in a match where the approaches failed to mesh, with frequent clinching spoiling the fight.
The officials had it 96-94 in favor to Buatsi, with the final judge a even score.
"It wasn't my finest performance but what defines champions? They succeed," the victor commented in the arena as he was greeted with negative reactions from the crowd.
The British fighter returned to winning ways after his first professional defeat - an epic battle with Callum Smith in February - to secure a twentieth professional win.
Various analysts believed Parker, thirty-one, should have been awarded the win but the Derbyshire fighter suffered the second setback of his 28-fight professional journey.
The Champion Claims Triumph in Dull Match
His career development has stalled in recent years through promotional disputes and considerable time of lack of fights.
Once tipped as the next star of the British fight scene, he now is positioned trying to achieve expectations - possibly in what appears to be a ultimate opportunity - under fresh management.
He opened tentatively, with the two boxers prepared to overcommit in a cagey initial rounds.
The challenger, whose only previous defeat came at super middleweight against John Ryder in two years ago after damaging his hand during the bout, was participating in his second appearance at light heavyweight.
By the middle rounds, the underdog had kept it close, making life awkward for the favorite, who operated with a protective stance to narrowly win the more effective stanzas.
The audience's tolerance diminished amid regular grabbing, with the challenger falling to the floor multiple occasions during grappling.
Parker closed well, but several stanzas were challenging to assess. Although, ex-champion Carl Frampton - working with the broadcast network - had it particularly wide for the challenger, giving Buatsi just a single round.
The victor progresses, but with the likes of power puncher David Benavidez, and Eastern European fighter Bivol dominating the weight class, the road to world glory - on this evidence - still appears challenging.
Ricky Hatton Tribute Inspires Manchester Derby Battle
In the co-main event, Lyndon Arthur overcame Rea by close verdict in a excellent local rivalry fight to capture the European light-heavyweight title.
The venue became quiet for a extremely emotional tribute before the fight as 10 bells tolled in remembrance of local hero Hatton, who passed away at age 46 in last month.
It was the first major televised match card in the location since Hatton's death. As the final chime ended, the quiet became a chant of "only one Ricky Hatton".
The competition within the ring reflected the sentiment. The eventual winner was sent to the canvas by a significant blow directly to the chin in the second round, standing uncertainly to his position on the eight count.
But the traditional red equipment of Arthur soon came forward again. From the other corner, the opponent - in opposing blue - was marked up early, significant bruising developing under his face as the fighters landed punishing blows.
The challenger, 27, connected with strong blows but the champion, 34, fought fire with fire with powerful upward punches as the action hardly diminished over twelve rounds.
Arthur edged the result with scoring tallies of even score, 115-113 and 115-112, but both fighters were determined and full of heart, exactly what their hero Hatton stood for.
