An electrochemical sensor was developed based on the pyrochlore-type binary metal oxide samarium stannate nanoparticles (Sm2Sn2O7 NPs). The Sm2Sn2O7 NPs were prepared using the co-precipitation technique, and they were subjected to physiochemical characterizations such as X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The morphological and elemental information was interpreted by field-emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM) analysis. The electrocatalytic sensing of the pharmaceutical drug azathioprine (AZN) was exhibited using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) over the Sm2Sn2O7/GCE (GCE - glassy carbon electrode). The Sm2Sn2O7/GCE had high electrocatalytic behavior for AZN determination with a limit of detection of 4 nM and superior sensitivity of 0.27 μA μM–1 cm–2, and it has a linear range from 0.01 to 948 μM. Furthermore, the Sm2Sn2O7/GCE exhibited excellent selectivity, long-term storage stability, good repeatability, and reproducibility for AZN detection. Additionally, the Sm2Sn2O7/GCE sensor possessed considerable importance for the sensing of AZN in biological fluids for practical applications. We believe that this pyrochlore-based Sm2Sn2O7 NP electrocatalyst can act as a prospective electrode material for the electrochemical determination of AZN in clinical biological applications.