The Society was formed based on the efforts of two local societies, the Woolhope Naturalists' Field Club of Hereford and the Yorkshire Naturalists' Union. The curator of the Hereford club, Dr. H.G. Bull, convinced the members in 1867 to undertake the particular study of mushrooms. While the mycological efforts of the club diminished somewhat upon the death of Dr. Bull, the Union of Yorkshire took the lead and founded its mycological committee in 1892. This committee attracted many eminent mycologists including Mordecai Cubitt Cooke (1825-1914), Carleton Rea (1861-1946), George Edward Massee (1850-1917), Charles Bagge Plowright (1849-1910) and others.
The need for a national organization and the need for a journal to publish their observations led M.C. Cooke, C. Rea, G.E. Massee, Charles Crossland (1844-1916) and other mycologists to found the Society in 1896. Elected as the first officers were G.E. Massee as president, C. Crossland as treasurer, and C. Rea as secretary. The choice of G.E. Massee for president was based on his international reputation (he had more than 250 mycological publications) and his role as the mycologist at the Royal Botanical Gardens of Kew (where he had replaced M.C. Cooke as mycologist in 1893). In 1897, C. Rea assumed the function of treasurer, remained secretary until 1918 and was editor until 1930.
By 1903 the Society had over a hundred members, by shortly after World War II it had over four hundred members, and by 2006 membership reached over two thousand.
Starting in 1896 the Society began publishing the Transactions of the British Mycological Society. In 1989 the Transactions were renamed Mycological Research which in turn was renamed Fungal Biology in 2010. In 1967 the Society began publishing the Bulletin of the British Mycological Society. In 1987 the Bulletin was renamed The Mycologist which in turn was renamed Fungal Biology Reviews in 2007 and launches a new journal Fungal Ecology. In 2000, the Society began publishing the quarterly journal Field Mycology for the study and identification of wild fungi. Periodically, the Society publishes symposia in the British Mycological Society symposium series on a particular theme. The first one, Genetics and physiology of Aspergillus edited by John E. Smith and John A. Pateman, was published in 1977. There have been twenty-four symposia published as of 2006.
The Society also publishes many other items, from fine art prints to illustrated pocket identification guides, as well as a range of curriculum resources for teachers.
In addition to meetings and publications, the Society is involved in the teaching of mycology. It organizes regular field-trips, both in the United Kingdom and abroad, often in formal association with the mycological society in the host country, as for example, the 1952 series of field-trips in France in concert with the Société mycologique de France.
In 1971 under the leadership of then president Terence Ingold, the Society organized and hosted the first international congress of mycologists at Exeter. Eight mycological societies were represented.