A vehicle lower section structure including: rockers; a floor tunnel; and a floor cross member that extends along the vehicle width direction and couples the rocker and the floor tunnel together, that includes an upper wall, a front wall extending downward from a front end portion of the upper wall, and a rear wall extending downward from a rear end portion of the upper wall that together with the floor panel configure a closed cross-section, wherein of the front wall and the rear wall, a first cutout portion is formed in a lower edge of an end portion at the rocker side of the wall further from a center pillar, and a second cutout portion that is smaller than the first cutout portion is formed in a lower edge of an end portion at the rocker side of the wall closer to the center pillar.