The Library was established by the will of Dr Daniel Williams, the leading London nonconformist minister of his day, who died in January 1716. He left instructions for his trustees to house his collection as a public library and to make it available to nonconformist ministers, tutors and students in the City of London. In 1890 the Library moved to its current home in a Grade 2 Listed building built in 1849 and located on Gordon Square. Gothic in style, the building was originally built as a hall of residence for University College London and remarkably the library retains the original drawings and specifications.

The building is in need of structural repair and in consultation with CPMG the Library Trustees are taking the opportunity to comprehensively re-think the site, including extending the building to provide more archive space and reconfiguring internal spaces to improve access to the library whilst increasing income by re-purposing under used space as lettable offices.