Introduced here is a lightweight, foldable seat cushion which can be placed in the shopping cart seat to support a child's legs, and prevent the hard surfaces of the shopping card, such as bars, from causing discomfort to the child and causing the child to try to get out of the cart. The seat cushion can attach to the cart using an attachment mechanism such as magnets and/or clasping protrusions, thus preventing the movement of the seat within the cart. The seat cushion can fold for easy storage in a diaper bag. The lightweight, and the compact size of the seat cushion makes the carrying of the seat cushion convenient and effortless.