British light-heavyweight Buatsi made a winning yet disappointing beginning to his career under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's activity level likely gained him a split decision in a competitive ten-round fight at the Manchester venue.
But Parker landed significant shots, delivering effective clean blows in a contest where the styles didn't complement each other, with frequent clinching marring the action.
Two judges judged it 96-94 to the winner, with the remaining official a even score.
"It wasn't my best showing but how do champions respond? They prevail," the victor said in the ringside as he was greeted with boos from the crowd.
The Londoner got back to winning after his maiden career setback - an thrilling contest with Callum Smith in last winter - to claim a 20th career victory.
Various analysts thought Parker, 31, deserved the win but the Derbyshire fighter suffered the second setback of his 28-bout professional journey.
Buatsi Secures Win in Dull Encounter
His career development has stalled in the past few years through promotional disputes and considerable time of inactivity.
Previously predicted as the future of the British fight scene, he now is positioned trying to fulfil that early promise - possibly in what appears to be a final roll of the dice - under fresh management.
He began cautiously, with the two boxers prepared to overcommit in a tentative opening few rounds.
Parker, whose sole prior loss came at the lower weight class against his former opponent in two years ago after suffering a hand injury during the bout, was competing in only his second bout at the higher weight class.
By the middle rounds, the underdog had stayed in contention, creating difficulties for Buatsi, who operated with a protective stance to narrowly win the more effective periods.
The spectators' acceptance wore thin during constant clinching, with the challenger falling to the floor several times during close exchanges.
Parker ended stronger, but several stanzas were challenging to assess. Although, ex-champion Carl Frampton - working with Dazn - had it significantly in favor for Parker, giving Buatsi just one round.
The victor moves on, but with the likes of power puncher Benavidez, and Russian champion Dmitry Bivol ruling the division, the road to world glory - based on this performance - still appears challenging.
Ricky Hatton Homage Motivates All-Manchester Battle
In the secondary fight, Arthur defeated Rea by split-decision in a excellent local rivalry battle to capture the European light heavyweight title.
The arena fell silent for a deeply poignant homage ahead of the contest as 10 bells rang in remembrance of Manchester's own Hatton, who passed away aged 46 in recently.
It was the initial significant broadcast match card in the location since the passing of Hatton. As the final chime ended, the quiet became a roar of "there's just one Ricky Hatton".
The fighting during the bout reflected the sentiment. Arthur was floored by a significant blow flush on the face in the second round, rising shakily to his footing on the count of eight.
But the traditional red attire of Arthur soon advanced again. On the opposite side, the opponent - in opposing blue - was marked up soon, noticeable damage forming under his face as the fighters exchanged punishing blows.
Rea, twenty-seven, landed power punches but Arthur, 34, responded in kind with effective uppercuts as the intensity rarely dropped over 12 rounds.
The victor narrowly won the result with judges scorecards of draw, narrow lead and 115-112, but each competitor were relentless and full of heart, all the qualities their inspiration the legend represented.
