Electrochemical NO reduction reaction (NORR) to NH₃ emerges as a fascinating approach to achieve both the migration of NO pollutant and the green synthesis of NH₃. In this contribution, within the framework of computational hydrogen model and constant-potential implicit solvent model, the NORR electrocatalyzed by a novel transition-metal-anchored SnOSe armchair nanotube (TM@SnOSe_ANT) was investigated using density functional theory calculations. Through the checking in terms of stability, activity, and selectivity, Sc- and Y@SnOSe_ANTs were screened out from the twenty-five candidates. Considering the effects of pH, solvent environment, as well as applied potential, only Sc@SnOSe_ANT is found to be most promising. The predicted surface area normalized capacitance is 11.4 μF/cm², and the highest NORR performance can be achieved at the U_RHE of −0.58 V in the acid environment. The high activity originates from the mediate adsorption strength of OH. These findings add a new perspective that the nanotube can be served as a highly promising electrocatalyst towards NORR.