Sankt Peter am Hart (also written St. Peter am Hart) is a municipality in the district of Braunau in the Austrian state of Upper Austria. It lies in the Innviertel region of the country, near the border with Germany.
The municipality is located in the Alpine foothills of Upper Austria, in the valley of the Inn River, which forms the nearby border with Bavaria. The surrounding area is rural and agricultural, typical of the Braunau district.
Like other municipalities in the district, Sankt Peter am Hart is administered as a single local authority and is part of the Innviertel, a region historically connected to Bavaria before becoming part of Upper Austria in the late eighteenth century.