Silicon–oxide–nitride–oxide–silicon (SONOS) capacitor devices with an oxy-nitride as the charge-trapping layer (O-SONOS) could be candidates for UV total dose (TD) nonvolatile sensors. UV radiation induces a significant increase in the threshold voltage VT of the O-SONOS UV TD nonvolatile radiation sensors. The experimental results indicate that the UV-induced increase in VT for the O-SONOS capacitor device under positive gate bias stress (PGBS) is nearly 2 V after 100 mW∙s/cm2 TD UV radiation. The change in VT for the O-SONOS capacitor after UV irradiation is also correlated with UV TD up to 100 mW∙s/cm2 irradiation. The charge-retention loss of the nonvolatile O-SONOS capacitor after a 10-year retention is below 10%. The UV TD information can be permanently stored and accumulated in nonvolatile O-SONOS capacitor devices. The O-SONOS capacitor device used in this study has demonstrated the feasibility of nonvolatile UV TD sensing.