A series of Eu3+/Bi3+ single and co-doped La2MgSnO6 phosphors are synthesized by the solid-state method. The crystal structure, optical properties, energy transfer processes, and thermal stability of phosphors are investigated systematically. Under 331 nm excitation, both the orange-red emission of Eu3+ ions ranging from 500 to 750 nm and the blue emission band centered at 403 nm are observed in the La2MgSnO6:Eu3+, Bi3+ samples. With the doping concentration of Eu3+ changing, the emission of La2MgSnO6:Eu3+, Bi3+ phosphors can be adjusted from blue (0.219, 0.350) to orange-red light (0.644, 0.341) in chromaticity coordinate. Furthermore, the security ink prepared by phosphors can be effectively used for encryption writing and anti-counterfeit marking. Additionally, the latent fingerprint developed using La2MgSnO6: Eu3+, Bi3+ phosphor demonstrates excellent contrast and sensitivity.