He first worked as a rock musician, forming a band in 1968, (Sign of Life, later Ankh), which were signed by Vertigo, but split up after Vertigo rejected the finished product.  In 1969/70 Rohl completed an Institute of Incorporated Photographers degree at the University of Manchester, before forming a new group, Mandalaband, which released two albums, Mandalaband (1975 - "an ambitious concept inspired by the Chinese occupation of Tibet") and The Eye of Wendor (1978). About 1974, Rohl started work as a sound engineer, ultimately becoming chief engineer at Strawberry Studios, the Stockport home of the group 10cc. Royalties from four solo artist and composing recording contracts enabled him to retire from music and focus on Egyptology, in particular to develop the New Chronology which he had been working on for five years during his music career.

In 1985 Rohl became the first Director of the Institute for the Study of Interdisciplinary Sciences (ISIS), and editor of its Journal of the Ancient Chronology Forum since 1986. In 1988 he was accepted by University College, London and awarded the prestigious W.F. Masom History Research Scholarship by the University of London as well as being awarded his degree in Ancient History and Egyptology in 1990. He then began his research on a doctoral thesis entitled "A re-examination of the Chronology of the Third Intermediate Period in Egypt" but failed to complete the PhD due to long-term book writing and TV commitments.[citation needed] He is a past President of the Sussex Egyptology Society (SES) and edits the Eastern Desert Survey Report. He excavated at Kadesh in Syria for the London Institute of Archaeology during the 1990s, and is currently Co-Field Director of the Eastern Desert Survey in Egypt.

The publication of his book, A Test of Time led to his role in a three-part television documentary, "Pharaohs and Kings: A Biblical Quest", which appeared late summer 1995 on Channel 4 in the UK, and spring 1996 on The Learning Channel/Discovery in the USA.

Following a thirty-year break from music composition and production, Rohl reformed a new incarnation of Mandalaband to release the first album of a two-part progressive rock concept work, BC - Ancestors, in 2009, and followed by its partner album, AD - Sangreal, in 2011. BC - Ancestors follows the Old Testament story of humanity from the Garden of Eden through to the birth of the Roman Empire. AD - Sangreal follows on, describing the contemporary history and legends of the Sangreal (Holy Grail), from the Last Supper over the next 1000 years.