USS Ontario may refer to the following ships of the United States Navy:
was a lake schooner in the United States Navy during the War of 1812 was a 16-gun rated sloop-of-war in the United States Navy during the years following the War of 1812 A Java-class steam frigate was laid down in 1863 as Ontario, renamed New York in 1869, and sold while still on the stocks, in 1888 Another Ontario was launched in 1908, decommissioned 7 April 1913, converted into a repair ship and renamed in 1914 was a single screw seagoing tugboat commissioned in 1912 and served until 1946
See also Ontario (disambiguation)