Jason Horsley is a self-described philosopher. He is the youngest child of Valerie Walmsley-Hunter and Nicholas Horsley, the chairman of Northern Foods from 1970 until the role was assumed by Christopher Haskins; the company had been founded by Nicholas's father, Alec. Jason Horsley had an older brother painter and author Sebastian Horsley who died of a suspected heroin overdose in June 2010, and an older sister, a psychotherapist named Ashley.

In 1991, Horsley disinherited his personal fortune and traveled to Morocco to live on the streets.

In 1999, Horsley published his first book, a two-volume study of violence in cinema, entitled The Blood Poets, from Scarecrow Press. The book was dedicated in part to the retired New Yorker film critic, Pauline Kael. In 2003, Horsley published Matrix Warrior: Being the One (Orion Publishing Group), in which he combined the plot of the 1999 movie The Matrix with the teachings of Carlos Castaneda, and argued that reality is an illusory construct designed to enslave humans and drain their life-force as food for "inorganic beings".

In 2002, he made a six-part digital film series called The God Game: An Investigation Into the Illusory Nature of Reality, and in 2008 a short film, Being the One: Document of a Delusion, followed. These are viewable on YouTube.

More recently, in 2008, Horsley began a series of weekly podcasts called "Stormy Weather: News from the Front Line in the End Times," under the pseudonym of Aeolus Kephas, the name under which he also published The Lucid View: Investigations into Occultism, Ufology, and Paranoid Awareness, in 2003 (Adventures Unlimited Press). After the first run of podcasts (which ended in March 2009), he revealed his actual identity and soon after, in August 2009, began a second series of podcasts, "Warty Theorems: Identity Deconstruction & Pattern Recognition in the End Times." In the interim, Horsley started a "Stormy Weather" forum, where he posts as "Ghost of Elvis," and began SWEDA, or "Stormy Weather Existential Detective Agency." SWEDA is a private, paid subscriber area of the forum.

Under the name of Jason Kephas, he also hosts a weekly podcast called "Vagabond Blues: Wanderings of a Galactic Mind."

Horsley's film analyses have appeared in various publications, including New Dawn magazine, Bright Lights Film JournalFilm & Festivals Magazine Cineaste and The Guardian. He worked as a contributing editor and film reviewer for Oaxaca Times in Oaxaca, Mexico, in 2004, and wrote film reviews for The List , an Edinburgh-based publication, in 2007-8.

His first work, The Blood Poets: A Cinema of Savagery 1958-1999, was well reviewed by Salon. In 2005, Horsley published Dogville Vs. Hollywood: the War Between Mainstream Movies and Independent Cinemafrom Marion Boyars, UK.

His most recent books (both 2009) are Homo Serpiens: An Occult History of DNA from Eden to Armageddon, under the name of Aeolus Kephas (Adventures Unlimited Press), and The Secret Life of Movies: Shamanic and Schizophrenic Journeys in American Movies, published under his given name, by McFarland & Company.

In 2010, he self-published a short, illustrated book called Paper Tiger: A Mythic Narrative, under the name of Jason Kephas. The book apparently recounts Horsley's experiences of growing up with his brother, Sebastian Horsley, and the effects of his brother's tell-all autobiography Dandy in the Underworld.