Baigent was born in March 1948 in Christchurch, New Zealand. He grew up in Motueka and Wakefield, small communities on the sparsely-populated South Island of New Zealand. His upbringing was Catholic, and he attended church three times a week, as well as being tutored in Catholic theology from the age of 5. His father left the family when he was 8 years old, and Baigent took the name of his maternal grandfather, Lewis Baigent. His great-grandfather had founded a forestry firm, "H. Baigent and Sons".

His secondary schooling was at Nelson College, and then he moved on to Canterbury University, Christchurch, initially intending to study science and continue in the family career of forestry, but then switched to studying comparative religion and philosophy, studying Buddhism, Hinduism and Christianity. He traveled to Australia and Southeast Asia, occasionally living on the street. He then returned to Auckland, receiving a BA in Psychology.

Michael Baigent worked briefly at the BBC photographic department, and worked night shifts at a soft-drink factory. Later in life, Baigent earned an MA in Mysticism and Religious Experience at the University of Kent. Michael Baigent from HarperCollins Publishers

A Freemason and a Grand Officer of the United Grand Lodge of England, he has been editor of Freemasonry Today since April 2001, which he has used as a platform for a more liberal approach to Freemasonry. He is a trustee of the Canonbury Masonic Research Centre.

He currently lives in Bath with his wife, Jane. They have two daughters, one of them named Tansi (born c. 1986).

In 1976, Baigent moved to England, where he met Richard Leigh, the man who was to be his roommate and frequent co-author. Leigh introduced him to the alleged mystery of Rennes-le-Château in France, and Baigent launched into research on the matter. In the same decade, Leigh introduced him to Henry Lincoln, an English television scriptwriter, while Lincoln was lecturing at a summer school. The three discovered that they shared an interest in the Knights Templar, and took their Jesus bloodline theory on the road during the 1970s, in a series of lectures which later developed into the 1982 book, The Holy Blood and the Holy Grail.

Published on 18 January 1982, The Holy Blood and the Holy Grail popularised the hypothesis that the true nature of the quest for the Holy Grail was that Jesus and Mary Magdalene had a child together, the first of a bloodline which later married into a Frankish royal dynasty, the Merovingians, and was all tied together by a society known as the Priory of Sion. This ideas were later used as a basis for Dan Brown's international bestselling novel The Da Vinci Code.

The evidence that Jesus and Mary were in a carnal (physical) relationship is an interpretation of the concepts of the Holy Kiss on the mouth (typically between males in early Christian times, thus signifying Mary's emancipation), and spiritual marriage, both discussed in the Nag Hammadi Gospels, particularly in the Gospel of Phillip. The idea was perpetuated by Laurence Gardner. While not conceding Christ's divinity, the psychological phenomenon of spiritual marriage was developed by Carl Jung in his theory of universal archetypes.

The day after the publication the authors had a public clash on television with the Bishop of Birmingham. The book rapidly climbed the bestseller charts, and had a sequel, The Messianic Legacy. The Holy Blood and the Holy Grail has reportedly, as of 2006, sold two million copies, with the film rights having been bought by Paramount.

Later, only with Leigh as co-author, he penned several books, including The Dead Sea Scrolls Deception (1991) in which they primarily followed the controversial theories of Robert Eisenman concerning the interpretation of the Scrolls.

Some of the ideas presented in Baigent's earlier book The Holy Blood and the Holy Grail, were incorporated in the bestselling American novel The Da Vinci Code, by Dan Brown.

In March 2006, Baigent and Leigh filed a lawsuit in a British court against Brown's publisher, Random House, claiming copyright infringement.

Concurrent with the plagiarism trial, Baigent released a new book, The Jesus Papers, amid criticism that it was just a reworking of themes from Holy Blood, Holy Grail, and timed to capitalize on the marketing hype around the release of the movie The Da Vinci Code, as well as the attention brought by the trial. In the postscript to the book (p. 355), Baigent points out that the release date had been set by Harper Collins long before.

On 7 April 2006, High Court judge Peter Smith rejected the copyright-infringement claim by Michael Baigent and Richard Leigh, and Dan Brown won the court case. On 28 March 2007, Baigent and Leigh lost their appeal against this decision and were faced with legal bills of about 3 million pounds.

Michael Baigent's interpretations of history sometimes attract hostile criticisms from scholars and historians. For example, Bernard Hamilton, writing in the English Historical Review (Vol. 116, No. 466 (Apr., 2001), pp. 474—475) described Baigent's treatment of The Inquisition in his 1999 book of the same name (with Richard Leigh) as pursuing "a very outdated and misleading account of this institution [the Inquisition]". In a review in the Spectator magazine (8 January 2000), reviewer Piers Paul Read said the authors: "show no interest in understanding the subtleties and paradoxes in the history of the Inquisition". However, on the book cover Ian Thomson of the Financial Times describes the book as "good popular history in a fast-paced narrative".

Sole Author

• Ancient Traces: Mysteries in Ancient and Early History (1998) ISBN 067087454X
• Exposing the Greatest Cover-Up in History (2006) ISBN 0-06-082713-0
• From the Omens of Babylon: Astrology and Ancient Mesopotamia (1994) ISBN 0140194800
• Racing Toward Armageddon: The Three Great Religions and the Plot to End the World (2009)

Co-written with Richard Leigh and Henry Lincoln

• The Holy Blood and the Holy Grail, 1982, UK ISBN 0-09-968241-9
• U.S. paperback: Holy Blood, Holy Grail, 1983, Dell. ISBN 0-440-13648-2
• The Messianic Legacy, 1986

Co-written with Richard Leigh

• The Dead Sea Scrolls Deception, 1991
• The Temple and the Lodge, 1989, ISBN 0-552-13596-8
• Secret Germany: Claus Von Stauffenberg and the true story of Operation Valkyrie, 1994
• The Elixir and the Stone: The Tradition of Magic and Alchemy, 1997
• The Inquisition. 1999

Co-written with other authors

• Mundane Astrology: Introduction to the Astrology of Nations and Groups (co-written with Nicholas Campion and Charles Harvey) 1984 (reissued expanded edition, 1992)