Abstract: A shopping cart seat liner, for use in protecting a shopping cart and its contents from contamination from a child seated therein, comprising a bottom panel, a front panel, a rear panel, and a pair of side panels. The bottom panel, front panel, rear panel, and side panels are attached to create a vessel which is open at a top lip for allowing the child to be seated: therein, and which is capable of folding flat prior to use. Leg cutouts are pre-scored on the front panel to create leg openings which allow the child's legs to extend outward from the seat liner therethrough.