[en] Orthophosphate-based phosphors have been used widely as efficient materials for the luminescence applications. Thermoluminescence (TL) properties of luminescent materials help us to find the suitability of the phosphors for the TL dosimetric application. In this work, a series of Dy${}^{3+}$ doped and Mn${}^{2+}$-codoped sodium yttrium phosphate Na${}_3$Y(PO${}_4$)${}_2$ phosphors were synthesized via a solid-state reaction method and thermoluminescence behavior were studied. To observe the effect of the dopant and codopants on phase purity and crystalline structure of phosphors, X-ray diffraction method analyses were carried. In addition, the morphological images were examined; chemical composition and functional groups were confirmed. Herein, the Dy${}^{3+}$-doped and Mn${}^{2+}$-codoped Na${}_3$Y(PO${}_4$)${}_2$ phosphors were irradiated by 1 kGy-dose γ-radiation and Na${}_3$Y(PO${}_4$)${}_2$:0.07Dy${}^{3+}$ showed a intense TL intensity peak at 178 °C, whereas Mn${}^{2+}$-Na${}_3$Y(PO${}_4$)${}_2$:0.07Dy${}^{3+}$, 0.07Mn${}^{2+}$ phosphors showed at 134 °C. The effect of codopant Mn${}^{2+}$ on the TL properties of Dy${}^{3+}$-doped Na${}_3$Y(PO${}_4$)${}_2$ phosphors and irradiation dose were investigated. The optimized Na${}_3$Y(PO${}_4$)${}_2$:0.07Dy${}^{3+}$ phosphor was showed a linear response to irradiation as a function of dose in the range of the 50 Gy–1.5 kGy. The glow curves were deconvolated and the TL kinetic parameters of phosphors were obtained by adopting various methods, revealing that the glow curves exhibited the second-order kinetics, and activation energies were calculated. The kinetic parameters of prepared samples were compared with the other TL materials. The obtained results confirm that the phosphors may have potential applications as TL dosimetry materials to measure low irradiation.