This study presents the thermoelastic stability of carbon nanotube (CNT) patterned composite conical shells in the framework of shear deformation theory (ST). The study includes two different boundary value problems. As the material properties are independent of temperature, the truncated conical shell is assumed to be under thermal load, and when the material properties are temperature dependent, the conical shell is assumed to be under axial compressive load. The modified Donnell-type shell theory is used to derive the basic equations for CNT patterned truncated conical shells. The Galerkin method is applied to the basic equations to find the critical temperature and critical axial load expressions of CNT patterned composite truncated conical shells in the framework of ST. The effect of changes in CNT patterns, volume fraction, radius-to-thickness and length-to-thickness ratios, as well as the half-peak angle on critical parameters within the ST, are estimated by comparison with classical shell theory (CT).