La₂O₃:Eu³⁺ nanofibers and nanobelts were fabricated by calcination of the respective electrospun PVP/[La(NO₃)₃ + Eu(NO₃)₃] composite nanofibers and nanobelts. For the first time, La₂O₂CN₂:Eu³⁺ nanofibers and nanobelts were successfully prepared via cyanamidation of La₂O₃:Eu³⁺ respective nanostructures employing NH₃ gas and graphite at high temperature. X-Ray powder diffraction (XRD) analysis indicates that La₂O₂CN₂:Eu³⁺ nanostructures are tetragonal in structure with space group I4/mmm. Scanning electron microscope (SEM) analysis reveals that the thickness and width of the La₂O₂CN₂:Eu³⁺ nanobelts are, respectively, ca. 192 nm and 1.67 ± 0.18 μm, and the diameters of La₂O₂CN₂:Eu³⁺ nanofibers are 173.61 ± 21.61 nm under the 95% confidence level. Photoluminescence (PL) analysis manifests that the La₂O₂CN₂:Eu³⁺ with different morphologies emits the predominant emission peaks at 614 nm and 622 nm originated from the energy levels transition ⁵D₀ → ⁷F₂ of Eu³⁺ ions under the excitation of 284 nm ultraviolet light. It is found that the optimum doping molar concentration of Eu³⁺ ions for La₂O₂CN₂:Eu³⁺ nanostructures is 3%. La₂O₂CN₂:Eu³⁺ nanofibers exhibit stronger PL intensity than the nanobelts under the same doping concentration. CIE analysis demonstrates that color-tuned luminescence can be obtained by changing the concentration of doping activator ions and morphologies, which could be applied in the fields of optical telecommunication and optoelectronic devices. The possible formation mechanisms of La₂O₂CN₂:Eu³⁺ nanofibers and nanobelts are also proposed. More importantly, the new strategy and construct technique are of universal significance to fabricate other rare earth oxycyanamide nanostructures with various morphologies.