Seating systems for shopping carts, and methods for retrofitting shopping carts with the seating systems, are provided. One seating system may include a seat post with wheel assembly, a cart attachment for connecting to a frame of the shopping cart, and a support member connecting the seat post to the cart attachment. The support member moves toward a basket of the shopping cart into a stored position for collecting the shopping cart with other shopping carts. The support member moves away from the basket of the shopping cart into an operating position.