An object is to provide a vehicle rear portion structure that improves rigidity of a vehicle rear portion. At a wheel house connecting member, both end portions in a vehicle transverse direction of a top surface portion are joined to joining stays that are provided at wheel houses, and lower portions of both end portions in the vehicle transverse direction of a vertical wall portion, that extends toward a vehicle lower side from the top surface portion, are joined to fixing members. Accordingly, vehicle rigidity between the wheel houses, that are connected by the wheel house connecting member at a rear portion of a vehicle, improves.