The observatory was completed in 1769, in time for King George III's observation of the transit of Venus that occurred on 3 June in that year.

By 1842, the building had become disused, and was taken on by the British Association for the Advancement of Science and became widely known as the Kew Observatory. Responsibility for the facility was transferred to the Royal Society in 1871. The National Physical Laboratory was established there in 1900 and from 1910 it housed the Meteorological Office. The Met Office closed the observatory in 1980.