Post Offices in Janesville, Wisconsin, United States SearchSearch SearchSearch View: Grid 1View: Grid 2View: Grid 3View: Grid 4View: Grid 5View: List Downtown Janesville Post Office No Reviews Favorite Phone: (608) 754-4881Retail Hours Janesville Post Office No Reviews Favorite Fax: (608) 754-3401Phone: (608) 754-5556Retail Hours