Current sensing with RDSON correction is disclosed. In an embodiment, a method comprises: measuring an approximate temperature of a MOS transistor switch by a temperature sensor to yield a measured temperature; calculating a corrected temperature from the measured temperature using a stored temperature sensor gain and offset correction function; measuring a gate drive voltage for the MOS transistor; calculating a voltage correction factor using a stored voltage correction function, wherein the stored voltage correction function is a function of the corrected temperature and the gate drive voltage; measuring a RDSON voltage drop across the MOS transistor switch to yield a measured RDSON voltage drop; and calculating the current using the measured RDSON drop and the voltage correction factor.