He met his first spiritual teacher, Ross Nichols, the founder of The Order of Bards, Ovates and Druids, when he was 11. He began studying with him when a teenager, and joined the Order when he was 18. He studied meditation with Olivia Robertson in Ireland, who later founded the Fellowship of Isis, and in his twenties he founded The Esoteric Society in London, which organised journeys for members to Bulgaria and Egypt, and hosted talks by well-known authors such as Gareth Knight, W. E. Butler, and Arthur Guirdham.
In 1975 Nichols died, and Carr-Gomm followed a Bulgarian teacher, Omraam Mikhael Aivanhov for seven years, giving talks on his teachings and helping with the translation and publishing of his books into English. He also travelled to Bulgaria and studied the work of Aivanhov's teacher, Peter Deunov, visiting Sofia annually for fourteen years, teaching Deunov's Paneurhythmy dance in England and at Findhorn in Scotland. In his thirties he turned to a study of psychology, taking a BSc degree at University College London and Jungian analysis, with plans to become an analyst. On discovering Psychosynthesis, he trained instead as a therapist at the Institute of Psychosynthesis in London and began a private practice.
In 1988 he was asked to lead the Order of Bards, Ovates and Druids. He organised the Order's teachings into a distance-learning course, and edited Nichols' Book of Druidry with John Matthews. Since that time, the Order has grown to become the largest Druid teaching order in the world, with Professor of History Ronald Hutton writing that 'the OBOD correspondence course arguably represents one of the major documents of British spirituality from the late twentieth century'.
Special Times: Listening to Children, with Dr. Rachel Pinney and Meg Robinson, The Children's Hours Trust 1985.
When the Flame and the Rose are One: Etchings by Liuben Dimanov with excerpts from letters by Rainer Maria Rilke edited and introduced by Philip Carr-Gomm. (Privately published 1986, Limited edition of 100 copies, each with twenty lithographs signed by the artist).
The Elements of the Druid Tradition, Element Books 1991.
The Druid Way, Element Books 1993, Thoth Publications 2006.
The Druid Animal Oracle, with Stephanie Carr-Gomm, Simon & Schuster, Fireside Books, USA and Australia 1994. Connections Publishing UK 1996.
The Druid Renaissance ed. Thorsons, HarperCollins, 1996. [Re-issued as The Rebirth of Druidry – Ancient Earth Wisdom for Today, 2003]
La Force des Celtes: L’Heritage Druidique — Entretiens avec Philip Carr-Gomm, Paco Rabanne and Philip Carr-Gomm, Michel Lafon, Paris 1996.
In The Grove of the Druids: The Druid Teachings of Ross Nichols, Watkins Books, 2002.
Druidcraft: The Magic of Wicca & Druidry, Thorsons, HarperCollins, 2002.
Druid Mysteries: Ancient Wisdom for the 21st Century, Rider,Random House, 2002.
The DruidCraft Tarot, with Stephanie Carr-Gomm, St.Martin’s Press, New York, 2004.
What do Druids Believe? Granta, 2005.
The Druid Plant Oracle, with Stephanie Carr-Gomm, St.Martin’s Press, New York, 2008.
Sacred Places: Sites of Spiritual Pilgrimage from Stonehenge to Santiago de Compostela, Quercus, 2008.