He studied law at the Katholieke Universiteit Leuven (Louvain), Chinese language, literature and art in Taiwan. He went to Hong Kong, before settling down in Australia in 1970. He taught Chinese literature at the Australian National University (Canberra), where he supervised the honours thesis of future Australian Prime Minister Kevin Rudd, and later (1987–93) was Professor of Chinese Studies at the University of Sydney. After that he returned to Canberra, where he has lived ever since.
In 1971, on the advice of his publisher, he decided to adopt a pseudonym before the release of Les habits neufs du président Mao, in order to avoid the risk of becoming a persona non grata in the People's Republic of China. He chose "Leys" after the main character of Victor Segalen's novel René Leys (published in 1922).
In 2004, he was awarded the Prix mondial Cino Del Duca.
Ryckmans's books on the Chinese Cultural Revolution, based on his first hand observation, give scathing descriptions of the cultural and political destruction, as well as denouncing the hypocrisy of its western defenders. Ryckmans is also a translator of Chinese literature, such as the Analects of Confucius, and The Treatise on Painting by Shi Tao. He writes in French and English.
The 2001 film The Emperor's New Clothes, directed by Alan Taylor, was based on Leys' novel The Death of Napoleon. Leys expressed distaste for the film, however; stating in an afterword accompanying a reprint of the novel that this "latter avatar [The Emperor's New Clothes], by the way, was both sad and funny: sad, because Napoleon was interpreted to perfection by an actor (Ian Holm) whose performance made me dream of what could have been achieved had the producer and director bothered to read the book."
- Shitao's Les propos sur la peinture du moine Citrouille-amère (translation and comments, 1970)
- La vie et l'oeuvre de Su Renshan, rebelle, peintre et fou (1971).
- Les habits neufs du président Mao (The Chairman's New Clothes: Mao and the Cultural Revolution, 1971)
- Chinese Shadows (Ombres Chinoises), (1974)
- Images brisées (1976)
- Human Rights in China (1979)
- Broken Images: Essays on Chinese Culture and Politics (trans. Steve Cox, London: Allison & Busby, 1981)
- Orwell, ou l'horreur de la politique (1984)
- La forêt en feu: Essais sur la culture et la politique chinoises (The Burning Forest: Essays on Chinese Culture and Politics) (1987)
- La Mort de Napoléon (The Death of Napoleon, 1986)
- ""The Chinese Attitude Towards the Past" (Forty Seventh Morrison Lecture, 16 July 1986), China Heritage Quarterly 14 (June 2008).
- L'humeur, l'honneur, l'horreur: Essais sur la culture et la politique chinoises (1991)
- Analects of Confucius (translation, 1997)
- Essais sur la Chine (Laffont, 1998, coll. "Bouquins")
- L'Ange et le Cachalot (1998)
- The Angel and the Octopus (collected essays 1983-1998, published February 1999) ISBN 1-875989-44-7
- Protée et autres essais (2001; awarded the 2001 Prix Renaudot de l'Essai)
- Deux années sur le gaillard d'avant (2002)
- Les Naufragés du Batavia (The Wreck of the Batavia: A True Story, 2003, was awarded the Prix Guizot)
- La mer dans la littérature française (Plon, 2003)
- Lu Xun's La mauvaise herbe (French translation)
- Other People's Thoughts - Idiosyncratically compiled by Simon Leys for the amusement of idle readers (Black Inc., 2007)
- The Hall of Uselessness: Selected Essays (Black Inc, 2011)
- Nicholas Stuart: "Kevin Rudd: An Unauthorised Political Biography", Scribe, 2007
- ^ Simon Leys: "Victor Segalen, les tribulations d'un poète en Chine", in Figaro Littéraire February 3, 2005
- Simon Leys: "The Burning Forest: 'Human Rights in China'" (1978).
- IMDb entry for The Emperor's New Clothes
- Warren, David, "How evil triumphs", Ottawa Citizen, June 10, 2007.
- Pierre Ryckmans, "Are Books Useless?" Extract from the 1996 Boyer Lectures.
- Ian Buruma, "The Man Who Got It Right" (review of The Hall of Uselessness), The New York Review of Books, August 15, 2013.
- An Interview with Pierre Ryckmans, Chinese Heritage Quarterly, June 2011.