UK light-heavyweight Buatsi secured a victory yet underwhelming beginning to life under recent management with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level appeared to earn him a judges' verdict in a competitive ten-round contest at the boxing arena.
But Parker found success, landing some telling individual punches in a fight where the approaches failed to mesh, with constant grabbing spoiling the contest.
The scoring judges judged it 96-94 to Buatsi, with the remaining official a 95-95.
"It wasn't my best display but how do champions respond? They win," Buatsi said in the ring as he was greeted with boos from the audience.
The British fighter got back to winning after his maiden career setback - an memorable fight with Callum Smith in February - to claim a twentieth professional win.
Some ringside observers thought Parker, 31, should have been awarded the win but the British boxer suffered the second setback of his 28-match career.
The Champion Secures Victory in Slow Affair
The fighter's advancement has stalled in recent times through contract problems and extended periods of inactivity.
Earlier forecast as the next star of UK boxing, he now is positioned trying to realize his potential - maybe in what appears to be a last chance - under new promotional backing.
He started carefully, with both competitors ready to overcommit in a cagey opening few rounds.
Parker, whose only previous defeat came at super-middleweight against John Ryder in two years ago after suffering a hand injury in the contest, was participating in his second bout at light-heavyweight.
By the fight's midpoint, Parker had kept it close, creating difficulties for Buatsi, who operated with a tight guard to barely take the better periods.
The crowd's patience decreased amid regular grabbing, with the challenger falling to the floor several times during close exchanges.
Parker closed well, but many rounds were challenging to assess. Although, previous titleholder the boxing analyst - providing analysis for the broadcast network - had it strongly leaning for the challenger, scoring for Buatsi just a single round.
Buatsi progresses, but with the caliber of heavy hitter Benavidez, and Russian star Dmitry Bivol ruling the division, the journey to titles - on this evidence - still appears challenging.
Ricky Hatton Tribute Fuels Manchester Derby Battle
In the secondary fight, Arthur overcame Rea by close verdict in a terrific local rivalry contest to secure the continental belt.
The stadium fell silent for a deeply poignant homage before the fight as 10 bells sounded in memory of local hero Ricky Hatton, who succumbed 46 years old in September.
It was the premier televised fight night in the location since Hatton's passing. As the concluding sound ended, the silence became a chant of "there's only one Hatton".
The fighting inside the ropes matched the emotion. Arthur was sent to the canvas by a powerful punch directly to the chin in the second round, standing uncertainly to his feet on the eight count.
But the Manchester United-red attire of the fighter soon pressed ahead again. On the opposite side, Rea - in opposing blue - was damaged early, noticeable damage forming under his eye as the pair exchanged hard punches.
Rea, 27, delivered effective strikes but Arthur, thirty-four, matched the intensity with powerful upward punches as the action seldom decreased over the full distance.
Arthur edged the verdict with scoring tallies of even score, close margin and clearer margin, but the two athletes were determined and courageous, exactly what their hero Hatton embodied.
