St Mary's Church or St Mary Immaculate Church is a Roman Catholic parish church in Falmouth, Cornwall, United Kingdom. It was built from 1868 to 1869 and designed by Joseph Hansom. The architecture of the church, according to Historic England is a blend of "Gothic and Burgundian Romanesque styles". It is located on the corner of Kimberley Place and Killigrew Street. It was extended by Hansom's son Joseph Stanislaus Hansom in 1881 and it is a Grade II listed building.