A vehicle body rear structure includes a left and right rear-side frame and a rear panel assembly. The left and right rear-side frames extend in the front-back direction of the vehicle body. The rear panel assembly forms a closed-cross-section section extending in the direction of vehicle width intersecting the rear-side frames, is provided to the back end of the rear-side frames, and configures the bottom of a vehicle body rear opening. The rear panel assembly is provided with a bulkhead that is disposed in the closed-cross-section section at the upper surface of the rear-side frames, and that partitions the interior of the closed-cross-section section with surfaces oriented in the direction of vehicle width.