British light heavyweight Buatsi earned a win yet unimpressive debut to life under recent management with a decision win over Parker in the Manchester arena.
The Olympic medal winner's activity level seemingly secured him a majority decision in a close ten-round contest at the boxing arena.
But the challenger landed significant shots, delivering effective individual punches in a contest where the approaches never quite clicked, with constant grabbing disrupting the fight.
Two judges scored it 96-94 for to Buatsi, with the third a 95-95.
"It wasn't my finest showing but what do champions do? They succeed," Buatsi said in the ringside as he was met by negative reactions from the audience.
The British fighter got back to winning after his maiden career setback - an epic battle with Callum Smith in February - to secure a 20th pro success.
Several boxing experts believed the challenger, thirty-one, should have been awarded the decision but the British boxer suffered the second loss of his 28-bout professional journey.
The Champion Claims Win in Uneventful Match
His career development has stalled in the past few years through promotional disputes and considerable time of lack of fights.
Once tipped as the rising talent of the British fight scene, he now stands trying to realize his potential - possibly in what feels like a last chance - under fresh management.
He began cautiously, with both competitors prepared to take risks in a calculated initial rounds.
Parker, whose sole prior loss came at the lower weight class against John Ryder in two years ago after suffering a hand injury during the bout, was competing in only his second bout at light heavyweight.
By the halfway stage, the underdog had stayed in contention, making life awkward for the favorite, who worked behind a tight guard to edge the cleaner stanzas.
The crowd's patience wore thin during regular grabbing, with the challenger slipping to the canvas multiple occasions during close exchanges.
Parker ended stronger, but multiple periods were hard to judge. However, former world champion the boxing analyst - working with Dazn - had it particularly wide for the challenger, scoring for Buatsi just only one stanza.
Buatsi progresses, but with the presence of power puncher Benavidez, and Russian champion Bivol dominating the weight class, the road to world glory - based on this performance - still appears challenging.
Ricky Hatton Memorial Fuels All-Manchester Battle
In the supporting bout, Arthur defeated Bradley Rea by close verdict in a terrific local rivalry contest to secure the European light-heavyweight title.
The venue fell silent for a deeply poignant homage ahead of the contest as a bell ceremony sounded in remembrance of Manchester's own Ricky Hatton, who succumbed 46 years old in September.
It was the premier televised match card in the location since Hatton's passing. As the last bell faded, the stillness gave way to a roar of "there's just one Hatton".
The competition inside the ropes matched the emotion. Arthur was floored by a left hook directly to the jaw in the early round, rising shakily to his position on the count of eight.
But the Manchester United-red equipment of the fighter soon came forward again. On the opposite side, Rea - in opposing blue - was injured soon, heavy swelling forming under his orbital area as the fighters exchanged punishing blows.
The challenger, twenty-seven, delivered effective strikes but the champion, 34, responded in kind with effective uppercuts as the action seldom decreased over the full distance.
The victor edged the decision with judges scorecards of even score, narrow lead and 115-112, but each competitor were persistent and brave, exactly what their inspiration the legend stood for.
