High-performance transparent heaters were fabricated on glass substrate using spray coating the solution processed single walled carbon nanotubes (SWCNT). Transparent heaters were treated with acid and alcohol mixture (10:1) to display high heating performance. The post treated SWCNT heater with 81% transmittance at 550 nm reached a steady-state temperature of 424 K with a heating rate of 0.6 K/s when 60 V is applied. The enhancement of electrothermal performance was studied in terms of heating rate, input power density and applied voltage. The enhanced heating performance attributed due to the effective wetting of the SWCNT network which intern reduce the sheet resistance of the conducting films. Defrosters realized using the post treated heater able to remove frost within a minute when 30 V was applied. The excellent power dependent heating performance with high stability indicates that the SWCNT heaters can be used in the temperature controlled heaters, smart windows and defrosters.