Electrochromic smart windows are a way to develop energy-efficient buildings, changing their transmission properties with the application of electricity. In this study, amorphous WO₃ (a-WO₃) films are deposited using the potentiostatic electrodeposition method in a three-electrode system and demonstrated as switchable electrochromic smart windows. The deposition potential is varied between −0.6 to −0.9 V among which the film deposited at −0.8 V showed better electrochromic property. The deposition duration is also varied from 200 to 500 s to optimize thickness and morphology. Structural characterization studies are done with analysing XRD and Raman spectra revealed amorphous nature of the films. Optical analysis showed a decreasing bandgap from 3.4 to 3.3 eV with increasing deposition time, attributed to reduced quantum confinement in thicker films. Electrochemical evaluations, including cyclic voltammetry and chronoamperometry, demonstrated improved charge capacity and coloration efficiency for films deposited at −0.8 V for 400 s. These films exhibited rapid switching speed, and high transmittance modulation (>92%) with colouration efficiency of 65 cm2/C.