Yes, you can use a 3-way LED illuminated switch with a dimmer, but the locator light on the dimmer should be switched to OFF for best performance. When a dimmer controlling LEDs with an ON-locator light is used with a 3-way illuminated or regular switch, current from the locator light can bleed through the circuit and cause ghosting of the lamps or flickering of the switch. Turning off the locator light will reduce the chance of this occurrence.