Radiation‐induced degradation in packaged metal–oxide semiconductor field effect transistors (MOSFETs) can be efficiently removed by an anneal treatment carried out at 350 °C for 10 min in N2. The electrical characteristics of the MOSFETs including threshold voltage Vth, transconductance Gm, and drain current Id were examined in the recovery of device performance. The irradiation was performed by a Co‐60 (γ‐ray) source with the irradiation total doses ranging from 10 K rads to 10 M rads. Experimental results show that the anneal treatment can be repeatedly performed on a sample after receiving multiple irradiation and the recovery behavior is quite good for each anneal treatment. The determination of the temperature and the anneal time are also discussed.