British light heavyweight Buatsi earned a win yet underwhelming debut to life under fresh promotional backing with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output appeared to earn him a majority decision in a close ten-round fight at the Co-op Live Arena.
But Parker had his moments, delivering effective single shots in a contest where the techniques failed to mesh, with frequent clinching marring the action.
The scoring judges judged it 96-94 in favor to Buatsi, with the final judge a 95-95.
"It wasn't my finest display but how do champions respond? They prevail," Buatsi commented in the ring as he was greeted with boos from the crowd.
The Londoner returned to winning ways after his initial pro loss - an epic battle with his previous opponent in February - to secure a 20th career victory.
Several boxing experts felt Parker, 31, should have been awarded the decision but the British boxer experienced the second defeat of his 28-match professional journey.
The Champion Earns Win in Dull Affair
Buatsi's progress has stalled in recent years through contract problems and extended periods of inactivity.
Previously predicted as the future of UK boxing, he now is positioned trying to fulfil that early promise - maybe in what appears to be a ultimate opportunity - under new promotional backing.
He opened tentatively, with the two boxers prepared to take risks in a cagey initial rounds.
Parker, whose only previous defeat came at super middleweight against John Ryder in two years ago after suffering a hand injury mid-fight, was competing in only his second appearance at light heavyweight.
By the fight's midpoint, the underdog had made it competitive, creating difficulties for Buatsi, who operated with a solid defense to narrowly win the better stanzas.
The spectators' acceptance wore thin because of constant clinching, with the challenger falling to the floor various instances during grappling.
Parker closed well, but several stanzas were hard to judge. Nevertheless, former world champion Carl Frampton - providing analysis for the broadcast network - had it strongly leaning for the challenger, giving Buatsi just one round.
The victor moves on, but with the caliber of power puncher David Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the road to world glory - judging by this showing - still looks steep.
Ricky Hatton Tribute Inspires Manchester Derby Battle
In the co-main event, Arthur overcame Rea by split-decision in a excellent Manchester vs Manchester fight to win the European light-heavyweight championship.
The venue grew hushed for a deeply poignant tribute prior to the bout as 10 bells tolled in remembrance of Manchester's own Ricky Hatton, who succumbed aged 46 in last month.
It was the initial significant broadcast boxing event in the location since Hatton's passing. As the concluding sound faded, the silence transitioned to a roar of "only one Ricky Hatton".
The action within the ring matched the emotion. Arthur was knocked down by a left hook flush on the jaw in the early round, rising shakily to his footing on the count of eight.
But the Manchester United-red equipment of Arthur soon came forward again. On the opposite side, Rea - in competitive blue - was injured quickly, heavy swelling appearing under his orbital area as the fighters exchanged punishing blows.
Rea, 27, landed power punches but Arthur, 34, fought fire with fire with effective uppercuts as the pace hardly diminished over twelve rounds.
Arthur barely secured the result with judges scorecards of draw, close margin and clearer margin, but the two athletes were relentless and brave, everything their idol the legend represented.
