Silver nanowires (AgNWs) with the length and diameter of 25–35 μm and 25–35 nm, respectively, were prepared via a polyol reduction process using FeCl3 and NaBr as reaction inhibitors. The molar ratio of FeCl3 to NaBr has an influence on the yield of the product, but has little influence on the morphology of the product. Transparent conductive AgNWs films were fabricated on a glass slide and the optoelectronic and electrothermal properties of the film were investigated. The experimental results reveal that AgNWs heated at 25–170°C remained intact, and fused into discontinuous segments after heated at 200°C; and AgNWs films have good conductivities (51.2 to 20.5 Ω sq−1), excellent transmittance values (96.3 to 95.7%), and low surface roughness values (12.7 to 18.3 nm). The transparent AgNWs film heaters show fast heat response to reach its steady-state temperature and good electro-thermal conversion behaviour at low input voltages.