This study employed solid-state synthesis to develop the green emitting Er3+-Yb3+:NaZr2(PO4)3, NASICON material. Using Rietveld refinement, the crystallographic variables of the synthesized phosphors were precisely calculated. The upconverting phenomenon was seen with naked eye when exposed to 980 nm laser radiation. The intermediate excited state dependency on the unusual photon number dependence on the green and red emission has been understood using the steady-state rate law equations. Further, the temperature sensing performances with good repeatability were compared with different laser densities, and it was found that the prepared phosphors could be an ideal material for upconverting and temperature sensing applications.