The US Post Office-Johnstown is a historic post office building located at 14 North William Street in Johnstown, Fulton County, New York.

It was designed and built in 1912–1913, and is one of a number of post offices in New York State designed by the Office of the Supervising Architect of the Treasury Department, James Knox Taylor.

The original section is a five-by-seven-bay, 1-story limestone structure on a granite foundation in the Classical Revival style.

The entrance portico features four Doric order columns supporting an entablature.

This article about a historic property or district in Fulton County, New York, that is listed on the National Register of Historic Places, is a stub.