Wipe down your leather seat with a damp washcloth, and inspect it for potential causes of the odor. Spilled food, drinks, sauces and other substances that have been left on your leather seat may be causing the odor and need to be cleaned off immediately if discovered.
Clean the leather seat with a high-quality leather cleaner or soap. Rub it into the leather with a washcloth, and then wipe the cleaner off with a dry, clean cloth.
Take the leather seat outside, and allow it to air out for several days. If the seat is in your car, open the windows or doors, and use fans to blow air through the car. Airing out leather is one of the most effective ways to help fade odors.
Apply leather conditioner to the seat with a clean washcloth. Allow it to soak in.
Place activated charcoal or baking soda underneath the seat to help absorb the odor.