UK light-heavyweight Buatsi secured a victory yet disappointing start to his career under new promoters with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's activity level likely gained him a majority decision in a competitive ten-round contest at the Co-op Live Arena.
But the challenger landed significant shots, landing some telling clean blows in a fight where the styles didn't complement each other, with frequent clinching spoiling the contest.
The scoring judges judged it 96-94 to Buatsi, with the third a 95-95.
"It wasn't my finest showing but what do champions do? They prevail," Buatsi stated in the arena as he was met by negative reactions from the spectators.
The British fighter bounced back after his maiden career setback - an epic battle with his previous opponent in last winter - to claim a 20th pro success.
Various analysts felt the challenger, 31, should have been awarded the win but the British boxer experienced the second defeat of his 28-fight career.
The Champion Claims Triumph in Dull Match
Buatsi's progress has slowed in recent years through contract problems and considerable time of inactivity.
Once tipped as the future of UK boxing, he now stands trying to realize his potential - maybe in what feels like a ultimate opportunity - under fresh management.
He started carefully, with the two boxers prepared to be aggressive in a calculated early stages.
The challenger, whose single earlier setback came at super middleweight against John Ryder in two years ago after suffering a hand injury during the bout, was participating in his second bout at light heavyweight.
By the fight's midpoint, Parker had kept it close, making life awkward for Buatsi, who utilized a tight guard to edge the better periods.
The audience's tolerance diminished during frequent holding, with the challenger going down various instances during grappling.
Parker ended stronger, but many rounds were challenging to assess. Nevertheless, previous titleholder the boxing analyst - providing analysis for the broadcast network - had it particularly wide for the challenger, giving Buatsi just one round.
Buatsi advances, but with the caliber of power puncher Benavidez, and Russian champion Dmitry Bivol ruling the division, the journey to titles - on this evidence - still appears challenging.
Ricky Hatton Homage Fuels Local Rivalry Battle
In the secondary fight, Arthur overcame Bradley Rea by close verdict in a outstanding Manchester vs Manchester battle to win the European light heavyweight title.
The arena became quiet for a profoundly moving tribute ahead of the contest as ten bells sounded in memory of the city's native Ricky Hatton, who succumbed at age 46 in September.
It was the premier televised match card in the city since the passing of Hatton. As the concluding sound ended, the stillness transitioned to a shout of "there's only one Hatton".
The competition within the ring matched the sentiment. Arthur was floored by a left hook squarely on the chin in the early round, standing uncertainly to his feet on the eight count.
But the Manchester United-red shorts of the fighter soon advanced again. Across the ring, the opponent - in rival City blue - was injured soon, significant bruising forming under his face as the pair traded powerful shots.
Rea, twenty-seven, delivered effective strikes but Arthur, 34, matched the intensity with powerful upward punches as the intensity seldom decreased over twelve rounds.
Arthur edged the decision with official scores of 114-114, close margin and 115-112, but each competitor were relentless and courageous, everything their idol the legend embodied.
