USS St. Mary's or USS St. Marys has been the name of more than one United States Navy ship, and may refer to:
, a galley built in 1798 and transferred to the United States Revenue Cutter Service in 1801, a sloop-of-war in commission from 1844 to 1873, also spelled USS St. Marys, a patrol boat in service from 1917 to 1918, an attack transport in commission from 1944 to 1946

See also

• St. Mary's, was a side-wheeled steamer acquired by the U.S. Navy and renamed in 1861
• CSS St. Mary, a Confederate States Navy ship captured in 1863 by Union forces and commissioned into the U.S. Navy as