[1] Massee had an early interest in natural history, publishing an article on British woodpeckers at the age of 16 and compiling a portfolio of botanical paintings.

Through the influence of Richard Spruce, a family relative, he was able to travel on a botanical expedition to Panama and Ecuador, where, despite considerable hardships, he collected orchids and other plants.

George Massee helped found the British Mycological Society in 1896 and was elected its first President, serving in that capacity from 1896 to 1898.

During his career, he published over 250 scientific and popular books, papers, and articles on fungi, myxomycetes, plant pathology, and natural history.

"[7][8] Massee's daughter Ivy assisted with the creation of his 1911 book British Fungi by illustrating 40 coloured plates for the publication.