The study investigates the impact of electrochromic glazing on indoor environments, providing valuable insights for the practical application of electrochromic glazing. Three rooms were constructed in Zhangjiakou City, China, equipped with different shading devices (electrochromic glazing, venetian blind, and base case of the glazing with no shading). Through experiments and simulations, the analysis of the overall indoor illuminance revealed that electrochromic glass, in its dark state, effectively reduces the average indoor illuminance while ensuring a uniform distribution of illuminance throughout the space, meeting the specified values for the discomfort glare index most of the time. During nighttime lighting, the average illuminance in room with electrochromic glazing was 42% higher than in the control rooms. In winter, the daily heat supply quantity in room with electrochromic glazing was 4.4%–21.9% higher than in the control rooms. In summer, the heat gain in room with electrochromic glazing was 19.1%–41.8% lower than in room with base case of the glazing. On a sunny day in winter, the room with electrochromic glazing exhibited more stable PMV values compared to the room with base case of the glazing, with a 20% increase in the duration of PMV thermal comfort compliance, but its Percentage of PPD values were inferior to the room with base case of the glazing. In summer, the room with electrochromic glazing outperformed both the room with venetian blind and the room wtih base case of the glazing in terms of PMV and PPD values.