UK light heavyweight Buatsi earned a win yet disappointing start to his career under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's punch output seemingly secured him a judges' verdict in a close 10-round fight at the Co-op Live Arena.
But the challenger found success, landing some telling clean blows in a match where the techniques never quite clicked, with excessive holding disrupting the fight.
The scoring judges judged it 96-94 for to the winner, with the remaining official a 95-95 draw.
"It wasn't my best performance but what do champions do? They win," Buatsi stated in the ringside as he was faced disapproval from the spectators.
The British fighter returned to winning ways after his maiden career setback - an memorable fight with Callum Smith in February - to secure a twentieth professional win.
Several boxing experts felt Parker, thirty-one, deserved the decision but the British boxer experienced the second loss of his 28-bout career.
Buatsi Earns Victory in Slow Encounter
His career development has stalled in recent years through contract problems and considerable time of inactivity.
Once tipped as the next star of the British fight scene, he now finds himself trying to realize his potential - perhaps in what feels like a final roll of the dice - under fresh management.
He opened tentatively, with the two boxers willing to take risks in a calculated early stages.
Parker, whose only previous defeat came at super middleweight against his former opponent in two years ago after breaking his hand during the bout, was competing in only his second bout at light-heavyweight.
By the middle rounds, the underdog had made it competitive, causing problems for Buatsi, who operated with a solid defense to edge the better periods.
The spectators' acceptance diminished amid frequent holding, with Parker going down various instances during clinches.
The underdog closed well, but many rounds were difficult to score. However, former world champion the boxing analyst - commentating on the broadcast network - had it strongly leaning for the challenger, awarding Buatsi just only one stanza.
The victor moves on, but with the caliber of hard hitter Benavidez, and Russian champion Bivol dominating the weight class, the journey to titles - judging by this showing - still seems difficult.
Hatton Tribute Inspires All-Manchester Battle
In the supporting bout, Lyndon Arthur defeated Bradley Rea by close verdict in a excellent local rivalry contest to capture the European light-heavyweight title.
The stadium became quiet for a deeply poignant homage before the fight as 10 bells rang in honor of the city's native Ricky Hatton, who passed away aged 46 in recently.
It was the first major televised fight night in the city since Hatton's passing. As the concluding sound ended, the stillness became a chant of "there's only one Ricky Hatton".
The competition during the bout equaled the emotion. Arthur was knocked down by a powerful punch squarely on the face in the initial stage, rising shakily to his feet on the count of eight.
But the red-colored shorts of the fighter soon pressed ahead again. On the opposite side, Rea - in competitive blue - was marked up quickly, heavy swelling appearing under his eye as the pair landed hard punches.
The challenger, 27, connected with strong blows but Arthur, thirty-four, matched the intensity with stinging uppercuts as the pace seldom decreased over 12 rounds.
The victor narrowly won the verdict with scoring tallies of even score, close margin and wider gap, but each competitor were persistent and full of heart, exactly what their idol the legend represented.
