St. Stephen is a Canadian town in Charlotte County, New Brunswick, situated on the east bank of the St. Croix River around the intersection of New Brunswick Route 170 and the southern terminus of New Brunswick Route 3. The St. Croix River marks a section of the Canada–United States border, forming a natural border between Calais, Maine and St. Stephen. U.S. Route 1 parallels the St. Croix river for a few miles, and is accessed from St. Stephen by three cross-border bridges.

Charlotte County is the most southwestern county of New Brunswick, Canada.