The aim of this study is to investigate the effect of carbon nanotube reinforcement in conventional carbon fiber reinforced composite on the buckling and postbuckling behavior of the laminated nanocomposite plate made of carbon nanotube and carbon fiber reinforcements in a matrix material. The method of representative volume element is utilized to perform the multiscale modeling of the problem. Initially, Boolean-based random sequential adsorption algorithm is utilized to model a nanoscale representative volume element of nanocomposite material to mimic the effect of randomly distributed (i.e. having random orientation and position) carbon nanotubes in a matrix material. After estimating the elastic properties of the nanocomposite material using representative volume element, another microscale representative volume element of carbon fiber reinforced in the nanocomposite (i.e. carbon nanotube reinforced matrix material) is modeled to evaluate the stiffness properties of the lamina formed of carbon nanotube–carbon fiber reinforced nanocomposite. The laminae are further stacked in the sequence of (45°/–45°/–45°/45°) to model a laminate. Thereafter, the evaluated stiffness properties of the lamina are employed to predict the effect of carbon nanotube reinforcement on buckling and postbuckling behavior of the laminated plates through nonlinear finite element method formulation based on the first-order shear deformation theory and von Karman’s assumptions. It is established that carbon nanotube reinforcement in carbon fiber reinforced composite lamina results in the enhancement of stiffness properties of the resulting carbon nanotube–fiber nanocomposite lamina, with more prevalent effect on the matrix-dominated properties—transverse and shear moduli—than the axial modulus. The increased stiffness properties result in the substantial improvement in the buckling load and postbuckling strength of the laminated plate made of carbon nanotube–carbon fiber nanocomposite material, for all volume fractions of carbon nanotube, loading and boundary conditions, geometric parameters (i.e. aspect ratio and width-to-thickness ratio), and matrix materials.