Ryman was born in Canada and moved to the United States at age 11. He earned degrees in History and English at UCLA, then moved to England in 1973, where he has lived most of his life. He is openly gay.

In addition to being an author, Ryman started a web design team for the UK government at the Central Office of Information in 1994. He also led the teams that designed the first official British Monarchy and 10 Downing Street websites, and worked on the UK government's flagship website www.direct.gov.uk.

Ryman says he knew he was a writer "before [he] could talk", with his first work published in his Mother's newspaper column at six years of age.He is best known for his science fiction; however, his first novel was the fantasy The Warrior Who Carried Life, and his revisionist fantasy Was has been called "his most accomplished work".

Much of Ryman's work is based on travels to Cambodia. The first of these The Unconquered Country (1986) was winner of the World Fantasy Award and British Science Fiction Association Award. His novel The King's Last Song (2006) was set both in the Angkor Wat era and the time after Pol Pot and the Khmer Rouge.

Ryman has written, directed and performed in several plays based on works of other writers.

He was guest of honour at Novacon in 1989 and has twice been a guest speaker at Microcon, in 1994 and in 2004. Ansible #199, February 2004 Ansible #79, February 1994 John Grant: Gulliver Unravels: Generic Fantasy and the Loss of Subversion - infinity plus non-fiction He was also the guest of honour at the national Swedish sf convention Swecon in 2006, at Gaylaxicon 2008, at Wiscon 2009, and at Åcon 2010.

Mundane Science Fiction is a sub-genre of science fiction focusing on stories set on or near the Earth, with a believable use of technology and science as it exists at the time the story is written, the Mundane SF movement was founded in 2002 during the Clarion workshop by Ryman amongst others. In 2008 a Mundane SF issue of Interzone magazine was published, guest- edited by Ryman, Julian Todd and Trent Walters.

He is currently at work on a new historical novel set in the United States before their Civil War.

Novels

• The Warrior Who Carried Life (1985)
• The Child Garden (1989)
• Was... (1992)
• 253, or Tube Theatre (1996 online, 1998 print)
• Lust (2001)
• Or, Have not Have (2005)
• The King's Last Song (2006 UK, 2008 US)

Collections

• Four novellas (1994)

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British Science Fiction Award

• The Unconquered Country for Best Short (1986)
• Air for Best Novel (2005)

World Fantasy Award

• The Unconquered Country Best Novella (1986)

Arthur C. Clarke Award

• The Child Garden for Best Novel (1990)
• Air (2005)

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Campbell Award

• The Child Garden for Best Novel (1990)

Philip K. Dick Award

• 253: The Print Remix, 1998

James Tiptree, Jr. Award

• Air (2005)