"End Police Brutality in Nigeria," was hand-written on a white t-shirt held up by the attacker after he netted the fourth goal in a 4-1 Serie A win over Atalanta in Naples.
Anger over abuses by the Nigerian police's notorious Special Anti-Robbery Squad (SARS) have erupted into widespread demonstrations in the African country.
The #EndSARS hashtag started on social media after a video showing what looked like a SARS officer attacking a man spread online.
Saturday's goal was the first in Italy for the 21-year-old in his third appearance.
Napoli paid French club Lille a club record fee of up to 80 million euros ($94.6 million) to bring the forward to southern Italy on a five-year deal.
ea/td