BEIJING—A prominent activist who called himself the “Super Vulgar Butcher” as he mocked and pressured Chinese officials was given an eight-year prison sentence Tuesday for subversion, the harshest sentence handed down in a sweeping crackdown on rights campaigners.

The Tianjin No. 2 Intermediate People’s Court handed down the sentence after finding activist Wu Gan guilty of subverting state power. Mr. Wu will appeal the sentence, his lawyer Ge Yongxi told the Associated Press.

Mr....