HONG KONG — One of China’s most prominent human rights lawyers was given a suspended three-year prison sentence on Friday after being convicted of subversion charges.

The lawyer, Li Heping, who has been in detention since 2015, received a four-year reprieve, a court in the port city of Tianjin said in a statement. That means he will not have to serve the sentence if he stays out of legal trouble during that time.

The sentence means Mr. Li will be released, but it effectively prevents him from practicing law in the near future, rights groups said.

During Mr. Li’s detention, the authorities harassed his family and prevented his wife, Wang Qiaoling, from seeking legal representation, Ms. Wang said in an interview last year.

Frances Eve, a researcher at the Chinese Human Rights Defenders, said the threat of a return to detention meant that Mr. Li and his family would continue to endure uncertainty. “He and his family are effectively prisoners for the next four years,” she said.

Mr. Li has represented some of China’s best-known dissidents and rights activists. He was detained in 2015 by the police during an expansive crackdown on dissent that targeted more than 250 lawyers, legal assistants and activists, in what the lawyers said was a political assault on their profession.

One of Mr. Li’s high-profile clients was the blind legal advocate Chen Guangcheng, who escaped house arrest and fled to the United States Embassy in Beijing in 2012. He has also represented practitioners of Falun Gong, a religious sect banned in China.

The No. 2 Intermediate People’s Court in Tianjin said Mr. Li had endangered national security and social stability by “attacking” the government and had “colluded” with religious activists and lawyers with “subversive ideologies.”

The trial was held behind closed doors because it involved state secrets, according to the statement posted online by the court. Mr. Li said he would not appeal, the statement said.

The crackdown by the Chinese authorities on lawyers and their associates has drawn condemnation from foreign jurists and legal societies. Last year, the United Nations’ top human rights official called on China to release a group of detained lawyers, including Mr. Li, expressing alarm over what he called a “very worrying pattern” of prosecution.