Zhou, 52, was a former director ofFengrui Law Firm which had defended victims of sexual abuse, dissident scholars, among others.
Announcing the sentence, the No 2 Intermediate People's Court in Tianjin said that Zhou would also be deprived of his political rights for five years.
Zhou, who was arrested in July last year as part of a nationwide crackdown on legal rights activists, pleaded guilty and told the court he will not appeal. He is the third 709 detainee to go on trial in Tianjin this week.
Zhou has long been influenced by anti-China forces and gradually established ideas to overturn the country's political system, state-run Xinhua news agency was quoted as saying in the court statement.
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Since 2011, Zhou has verbally attacked the socialist system and the "one country, two systems" policy that applies to Hong Kong and Macao, and incited confrontation, the statement said.
He used the law firm as a front for his subversive agenda, recruited like-minded lawyers and other staff and together they discredited judicial organs, attacked the judicial systems and promoted anti-government sentiment by interfering in and exaggerating sensitive cases.
"I plead guilty," Zhou said in his final statement, "My actions have brought instability and risks to society", the Xinhua report said.
Zhou's trial followed those of activists Zhai Yanmin and Hu Shigen, who were both found guilty of subverting state power by the same court.
Zhai was on Tuesday handed a three-year suspended sentence - considered relatively lenient by the standards of Chinese dissident prosecutions - for crimes that included waving banners and shouting slogans.