Saint (or St) Johnstown, Johnstoun, Johnston or Johnstone may refer to:
Ireland St Johnston, County Donegal, a village St Johnstown (County Donegal) (Parliament of Ireland constituency) Saint Johnstown or Ballinalee, County Longford, a village St Johnstown (County Longford) (Parliament of Ireland constituency)
Scotland Perth, Scotland, originally known as Saint John's Toun or St Johnstone St Johnstone F.C., a football club based in Perth
United States Saint Johnstown, Delaware, a stop on the now defunct Queen Anne's Railroad line between Ellendale and Greenwood
See also Johnston (disambiguation) Johnstown (disambiguation) Saint John (disambiguation) Saint John's (disambiguation)