An apparatus and method are provided for a flangeless air filter configured to be mounted onto a flat surface within an air intake system of an internal combustion engine. The flangeless air filter is comprised of a cone-shaped filter medium, retained between a base and a cap, that is fabricated to remove contaminants and particulate matter from an intake airstream. The base includes a pliable seal that forms an airtight connection between the flangeless air filter and the flat surface of the air intake system. A mounting bracket and fasteners may be used to attach the base to the flat surface, compressing the seal there between. In some embodiments, the mounting bracket may be incorporated into, and made a part of the base. A cap is disposed on a top of the flangeless air filter and configured to direct the intake airstream around the cap and toward the filter medium.