A flush actuator device with a foot pedal for actuating a flush action at a toilet is provided. The flush actuator device may replace or supplement a manual handle on a conventional toilet and allows flushing action to be initiated by depressing a foot pedal on a floor surface adjacent the toilet. With the flush actuator device, a flush action can be performed using the foot pedal without necessitating any contact with the other parts of the toilet which may be deemed dirty or unsanitary, particularly in public restroom settings. A method of installing the flush actuator device onto an existing toilet is provided. Further, a method for actuating flushing of a toilet using a flush actuator device having a foot pedal is described. The ability to retroactively fit the flush actuator device to an existing toilet eliminates the need for complicated and expensive plumbing fixture replacement.