Agglomeration effect on the electro-magneto-thermo elastic response of a hollow piezoelectric circular cylinder reinforced with carbon nanotubes (CNTs) is the main contribution of present work. The cylinder is subjected to an internal pressure, a distributed temperature field due to steady state heat conduction with convective boundary condition, a magnetic field in axial direction and a constant electric potential difference between its inner and outer surfaces or combination of these loadings. All the equivalent mechanical, thermal and piezoelectric properties of nano-composite cylinder are obtained using Mori-Tanaka model considering agglomeration effects. The governing equation in polarized form is shown to reduce to a second-order ordinary differential equation for the radial displacement. Considering mechanical boundary condition, this differential equation is analytically solved. The electro-magneto-thermomechanical stresses, the electric potential and radial displacement distributions in the structure are discussed in detail. The presented results indicate that the agglomeration and volume percent of CNTs have significant influences on the electro-magneto-thermomechanical behavior of the nano-composite cylinder. POLYM. COMPOS., 39:1594-1603, 2018