An apparatus and method are described for an on-chip reliability controller. For example, one embodiment of a processor comprises: a set of one or more cores to execute instructions and process data; a reliability controller to perform one or more self-test/diagnostic operations, the reliability controller to aggregate reliability data resulting from the self-test/diagnostic operations; a reliability estimator integral to the reliability controller to use the aggregated reliability data to perform a probability analysis to determine reliability estimates for one or more components of the processor; and a control unit integral to the reliability controller to adjust one or more variables and/or circuitry related to operation of the processor responsive to the reliability estimates.