A vehicle rear portion structure includes a cross member that extends in a vehicle width direction at a vehicle rear, a rear wheel house that accommodates a rear tire, a rear pillar that extends in a vehicle vertical direction, a reinforcing member that connects the rear pillar with the rear wheel house, and a joining member that connects a lower end portion of the reinforcing member with one end portion of the cross member. The rear pillar is divided into a general portion and a high-rigidity portion. The high-rigidity portion is connected to an upper end portion of the general portion and is specified with a higher rigidity than the general portion. The reinforcing member is connected to the high-rigidity portion.