Yes, you can leave a light switch on with a smart bulb. However, there are a few things to consider before doing so. First, if the light switch is connected to an outlet, the outlet will need to be powered on in order for the light to stay on. Second, smart bulbs typically have a lifespan of around 15,000 hours. So, if you plan on leaving the light on for extended periods of time, it may be worth investing in a higher quality bulb that will last longer.