The human rights activist was born in 1944 in Jiangxi Province. In 1964, he was admitted to the Beijing Civil Engineering College. During the Cultural Revolution in 1969, Ren was publicly denounced and humiliated as "traitor" and "enemy of the revolution".

In November 1978, Ren Wanding joined the Democracy Wall Movement in Beijing. On January 1, 1979 he founded the "Chinese Alliance for Human Rights" and the independent journal "Human Rights in China". On January 5, together with six other activists, he proclaimed at Beijing's Democracy Wall a "Chinese Human Rights Manifesto" of 17 points specifying the demands for basic civil rights in his country.

The arrest of the female activist Fu Yuehua, also a member of the Alliance, on January 9, after organizing a street protest, signalled the beginning of growing repression. On March 29 (together with Wei Jingsheng) another member of the Alliance was seized, and a few days later also Ren Wanding who had written a lengthy dazibao to protest the previous arrests. Ren was eventually sent (without a formal trial, by order of the police) to four years of "re-education through labor".

After his release in 1983, Ren became an accounting clerk, then obtained a post as a researcher in an economic think-tank. In the wake of the growing political disputes between reformers and conservatives in the CCP, Ren Wanding started to write critical commentaries for media abroad. An Ren got involved in the new student movement in April 1989 after the sudden death of the reformist (but already deposed) CP Secretary General Hu Yaobang.

A fervent public speech in favor of Hu Yaobang on Tiananmen Square, which was covered by media in Hong Kong and Taiwan, probably became the reason why he got quickly arrested after the bloody clampdown on the students' movement on June 4. Ren was formally indicted for "counter-revolutionary incitement" and sentenced to seven years in prison in early 1991.

In 1994 Ren received the Robert F. Kennedy Human Rights Award, but he was only released from jail in June 1996 after having served his sentence to the very last day. Ren Wanding continued his political activities. In 1998 he participated in the founding of the "Democratic Party of China", and in 2007 he published a "Human Rights Manifesto '07" and founded a website to monitor human rights abuses in China. In September 2007, Ren eventually left China, touring Hong Kong, Europe and the US in support of the Chinese rights movement. After obtaining a teaching post at the prestigious "Science Po" Institute of Political Studies in Paris, he continued to live in France.