Accepted manuscript version, licensed CC BY-NC-ND 4.0. Carbon nanotube (CNT) films are gaining traction in applications such as transparent conductive films, electro-magnetic shields and thin film heaters. However, to date, few cost-effective large-area CNT coating methods have been reported. Here, we present a roll-to-roll (R2R) slot-die coating process for thin film CNT heaters. In this process, a CNT suspension is continuously coated on a PET film substrate and subsequently dried and packaged. This process allows for continuous square-meter-size CNT coating. The electrical resistance and thermal map of these samples are measured by high definition infrared (IR) thermography. Anti−/de-icing demonstrations of R2R CNT coated samples are performed inside a cold room and outdoor atmospheric icing conditions. The successful R2R coating of CNTs and anti−/de-icing demonstrations show promise for application of CNTs in large area applications, such as the de-icing of ships, for which strict regulations are put in place for vessels operating in polar waters.