Abstract The different roles that ionic liquids can play in several aspects of electrochromic technology have been reviewed, from the advantageous synthesis of electrochromic polymers to their key role as substantial components of liquid, semi-solid, or solid electrolytes. The performance of resulting devices has been analyzed, showing correct optical behavior and sometimes impressive lifetimes. From this review, it can be concluded that ionic liquids are versatile compounds that can improve the current performance of electrochromic and other electrochemical devices.