A mounting structure for a handheld showerhead is provided with an integral vacuum breaker device that breaks the fluid communication between the shower pipe and the supply hose upon the occurrence of back pressure in the water supply system. The mounting structure comprises a mount body that is coupleable to a shower pipe at its inlet end and to a supply hose at its outlet end. A vacuum breaker is provided within the mount body in-line between the inlet end and the outlet end. When positive fluid pressure is applied to the vacuum breaker, water flows through the vacuum breaker to a supply hose and handheld showerhead coupled to the outlet end. When negative fluid pressure or back pressure is applied to the shower pipe, the vacuum breaker seals the channel within the mount body to break fluid communication between the inlet end and the outlet end, thus preventing the back pressure from drawing contaminated water through the supply hose and showerhead. A cradle for holding the handheld showerhead is pivotally coupled to the mount body, and the mount body is rotatable about the shower pipe. The handheld showerhead is thereby provided with a mounting structure that integrates a vacuum breaker for preventing contamination due to back pressure in the water supply system, while providing a full range of motion for mounting in a desired position.