TIANJIN, China—A Chinese civil-rights lawyer known for uncompromising tactics stood trial for subversion, the last to be tried among dozens of legal campaigners detained in a government sweep three years ago to curb their activism.

The trial of Wang Quanzhang in this port city Wednesday was closed to the public and proceeded amid smothering security, with police outside the courthouse taking away at least one of the 42-year-old lawyer’s supporters. During the trial, Mr. Wang fired his court-appointed lawyer, according to his...