A voltage margin controller, an IC included the same and a method of controlling voltage margin for a voltage domain of an IC are disclosed herein. In one embodiment, the voltage margin controller includes: (1) monitoring branches including circuit function indicators configured to indicate whether circuitry in the voltage domain could operate at corresponding candidate reduced voltage levels and (2) a voltage margin adjuster coupled to the monitoring branches and configured to develop a voltage margin adjustment for a voltage regulator of the voltage domain based upon an operating number of the circuit function indicators.