Electrochromic devices (ECDs), offering dynamic control over light transmission, are widely adopted in various applications such as displays, automotive systems, and smart windows. However, the commercialization of ECDs is hindered by their slow electrochromic switching rates, particularly in low-temperature environments where reduced ion mobility severely limits ECD performance. This study addresses these limitations by combining a highly transparent ZnO/Ag/ZnO transparent heater (TH) with ECDs, creating integrated electrochromic devices (IECDs). The IECDs demonstrate marked improvements in response efficiency for both bleaching and coloring processes, particularly under sub-zero temperature conditions. For instance, at ≈17.9 °C, the heated IECDs achieve remarkable performance enhancements, with reaction rates increasing by 235.8% for bleaching and 54.7% for coloring compared to the unheated counterparts. In addition, the IECDs exhibit broader optical transmittance ranges compared to unheated ECDs, further emphasizing the superior performance and versatility. These findings highlight the capability of IECDs to maintain robust functionality across a wide range of environmental conditions, including sub-zero temperatures. By efficiently addressing the long-standing issue of slow electrochromic response rates, the proposed IECD approach offers a reliable solution, paving the way for high-performance ECDs in diverse applications such as automotive displays, smart windows, and energy-efficient building systems.