A scion of the Chakri dynasty (his grandfather's sister was a cousin and consort of King Vajiravudh), Somtow was born in Bangkok but moved with his parents to England at the age of six months. English was his first language. Somtow was educated at Eton College and at St Catharine's College, Cambridge. He returned to Thailand in the early 1960s for a five-year period, during which he learned the Thai language. At age 11, Somtow wrote a poem called Kith of Infinity, which was published in the English-language Bangkok Post. Shirley MacLaine saw it, and thinking that it was written by a dead poet, included it in her autobiography, Don't Fall Off the Mountain. The poem contains the line "I am not a man", since Somtow was not yet an adult. It is thought this line caused MacLaine to assume that the poet was a woman.

As a science fiction writer, he is known for several series, among which are Mallworld, Inquestor, and Aquila. He was first published as Somtow Sucharitkul in the late 1970s in the pages of Asimov's and Analog science fiction magazines, and wrote several stories and novels under that name before changing his byline to S. P. Somtow for personal reasons.

In the horror genre, he wrote Vampire Junction and a series of related novels and stories. He was president of the Horror Writers Association from 1998 to 2000. His other horror books include the werewolf/American West novel Moon Dance, the zombie/American Civil War novel Darker Angels and the collections Tagging the Moon - Fairy Tales of L.A. and The Pavilion of Frozen Women. In 1997, he wrote the juvenile vampire novel, The Vampire's Beautiful Daughter. He also directed the cult horror film The Laughing Dead.

His novel Jasmine Nights, a semi-autobiographical novel set in Thailand in the 1960s, has become his best known fictional work.

He has also composed five symphonies and a ballet, Kaki. Other musical compositions include the "Requiem: In Memoriam 9/11", commissioned by the government of Thailand as a gift for the victims of the 9/11 events and inspired by the poetry of Walt Whitman, Emily Dickinson, and T. S. Eliot.

In 2000 he composed Madana, the first orchestral western opera by a Thai composer and based on a Thai language play by King Rama VI. The opera was in English. His second opera on a Thai theme, Mae Naak, premiered in 2003 and a third opera, Ayodhya, was first performed in November, 2006. His opera "The Silent Prince" will premiere in Houston on October 15, 2010. A fifth opera, "Dan no Ura", is scheduled to premiere in 2011 in Bangkok.

He is currently artistic director of the Bangkok Opera. In 2006 Somtow Sucharitkul conducted the first Wagner opera in Southeast Asia, Das Rheingold, as part of a five year project to bring the entire Ring Cycle to Southeast Asia by the year 2010.

When Nobel Prize laureate Wole Soyinka withdrew as keynote speaker at the 2006 S.E.A. Write Awards Ceremony in protest against the ousting of the elected government of Thaksin Shinawatra, Somtow, a critic of Thaksin, replaced Soyinka as keynote speaker. In his speech, Somtow berated Soyinka for boycotting the awards and claimed that in 50 years, he had never felt more free. Soon afterward, Somtow's opera Ayodhya was censored by state officials under the junta, who claimed that the on-stage death of the demon-king, Thotsakan, would constitute a "bad omen" for the military junta. Somtow agreed to modify the scene and was forced to sign a document giving officials the right to "immediately shut down the opera in mid-performance if, in their sole opinion, a breach of 'tradition' occurs."

Somtow has been critical of all sides in the political disputes following the 2006 Thailand coup. Although he was a critic of the populist government of Thaksin, Somtow stated that "The righteous indignation of Thaksin's opposition, however, went beyond the pale when they started to say that the poor shouldn't vote because they're too stupid." Somtow has praised Democrat Prime Minister Abhisit Vejjajiva for being, "so balanced, so reasonable, so intelligent, and so well thought through."

Somtow Sucharitkul won the World Fantasy Award for best Novella in 2002 for The Bird Catcher, and has been nominated four other times. He has won the International Horror Guild Award, the John W. Campbell Award in 1981, the Locus Award for Best First Novel (1982, for Starship & Haiku), the HOMer Award, the American Horror Award and numerous other awards. He has been nominated for two Hugos and five Bram Stoker Awards. In 2008, he became one of the first recipients of the newly created Silpathorn Kittikhun Award, given by the Office of Contemporary Art and Culture of Thailand's Ministry of Culture. The Silpathorn Kittikhun Award has been viewed as an alternative to the more "staid, traditional National Artist Awards."

image:Somtowqueen.jpg|Somtow with H.M. Queen Sirikit after "Sirikit Concerto"image:PrincessandCardinal.jpg|Somtow with HRH Princess Galyani Vadhana, and Cardinal Michai, at the Thailand premiere of Mozart's C Minor Mass.