Vacuum in between the folds of the fabric. Use an upholstery attachment and work the nozzle in, pausing for a few seconds to pick up the dirt. Turn the ottoman over and vacuum the fabric underneath as well.
Prepare a solution of 1/4 cup bleach-free detergent and 2 cups water. Alternatively, use a commercial upholstery cleaner or carpet shampoo.
Apply a small amount of the cleaning solution to a small area of the ottoman to make sure it does not harm the fabric. If the color does not run, proceed to the next step.
Dip a sponge into the cleaning solution and begin blotting the dirt. Scrub stubborn spots lightly taking care not to rub beyond the soiled area.
Blot the ottoman with a clean dry cloth and allow it to air dry.