We observed an induced thermal effect in Er3+/Yb3+-codoped silicate fibers (EYDFs) after gamma radiation. It is further found that the induced thermal effect is reversible under room temperature. This is the first report, to the best of our knowledge, on such a radiation-induced reversible thermal effect on EYDFs. This phenomenon, ascribed to radiation effect on EYDFs, can be used to design a novel fiber-optic temperature sensor with tailored properties.