UK light-heavyweight Buatsi secured a victory yet disappointing debut to life under new promoters with a decision win over Zach Parker in Manchester.
The Olympic medal winner's activity level likely gained him a judges' verdict in a competitive 10-round bout at the boxing arena.
But Parker found success, landing some telling individual punches in a match where the styles didn't complement each other, with excessive holding spoiling the action.
The officials judged it 96-94 to the winner, with the third a 95-95 draw.
"It wasn't my best showing but what defines champions? They win," the victor stated in the ringside as he was faced disapproval from the spectators.
The British fighter returned to winning ways after his first professional defeat - an thrilling contest with Callum Smith in February - to secure a 20th career victory.
Various analysts thought the challenger, thirty-one, should have been awarded the win but the British boxer suffered the second loss of his 28-match professional journey.
The Champion Secures Triumph in Uneventful Match
The fighter's advancement has slowed in the past few years through contract problems and considerable time of inactivity.
Previously predicted as the next star of British boxing, he now stands trying to fulfil that early promise - perhaps in what seems like a last chance - under recent support.
He opened tentatively, with neither fighter willing to overcommit in a calculated early stages.
Parker, whose sole prior loss came at the lower weight class against his former opponent in two years ago after damaging his hand in the contest, was participating in his second appearance at the higher weight class.
By the middle rounds, Parker had stayed in contention, causing problems for Buatsi, who utilized a solid defense to edge the better stanzas.
The crowd's patience wore thin amid constant clinching, with the challenger going down several times during clinches.
Parker closed well, but multiple periods were difficult to score. Nevertheless, former world champion the boxing analyst - providing analysis for the broadcast network - had it particularly wide for the challenger, awarding Buatsi just one round.
The victor moves on, but with the likes of heavy hitter Benavidez, and Eastern European fighter Bivol dominating the weight class, the journey to titles - judging by this showing - still looks steep.
Ricky Hatton Tribute Fuels Local Rivalry Contest
In the co-main event, Lyndon Arthur beat Bradley Rea by divided decision in a outstanding all-Manchester fight to win the European light-heavyweight belt.
The stadium fell silent for a deeply poignant tribute prior to the bout as 10 bells tolled in memory of the city's native Hatton, who died aged 46 in September.
It was the first major televised match card in the location since Hatton's passing. As the concluding sound ended, the stillness transitioned to a chant of "there's only one Hatton".
The fighting inside the ropes matched the feeling. The eventual winner was floored by a left hook flush on the chin in the second round, standing uncertainly to his position on the eight count.
But the Manchester United-red shorts of the fighter soon came forward again. On the opposite side, the opponent - in rival City blue - was marked up early, noticeable damage forming under his eye as the fighters exchanged hard punches.
The challenger, twenty-seven, connected with strong blows but the champion, thirty-four, matched the intensity with stinging uppercuts as the action seldom decreased over the full distance.
The victor narrowly won the verdict with scoring tallies of even score, close margin and 115-112, but the two athletes were relentless and courageous, all the qualities their idol the legend embodied.
