Self-activated compound serving as host sensitizer for trivalent rare-earth ions has been intensively studied, but only in more recent years did it extend to non-rare-earth ions. In the present work, it is demonstrated for the first time that the parity-forbidden Mn4+ red emission can be effectively enhanced by utilizing the strong parity-allowed absorption of O2--W6+ charge transfer band and the energy transfer from WO2 groups to Mn4+ ions. Hopefully, the presently studied self-activated Na2WO2F4 can be developed as stable color converter for field-emission displays.