Born in London, England, Allom was apprenticed in 1819 to the architect Francis Goodwin. He was a founder member of the Royal Institute of British Architects (RIBA), and produced designs for buildings in London, which he carried out himself, as well as working with the architect Sir Charles Barry on numerous projects.

He produced many illustrations for publications of a topographical nature in the mid 1800s, including Devonshire and Cornwall Illustrated