Knockdown Factors (KDFs) are proposed to take into consideration the remarkable drop in the experimentally observed critical load from the theoretical load calculated from linear buckling analysis. The drop is mainly attributed to the interactions amongst the closely spaced modes and the respective multiplicity of the alternate equilibrium configurations. The modes are coupled by geometric nonlinearity in which the imperfections play a synergistic role. NASA SP-8007 recommends a far more conservative KDF for the laminated composite cylindrical shell. In order to relieve the conservatism, this study includes numerical analysis to determine the buckling response of a laminated cylindrical shell containing geometric imperfections in the form of dimple and embedded delamination. In contrast to the lateral load-induced perturbation (which offers ease in modelling), this study examines the impact of stress-free dimple on KDFs. For delamination, the double-layered model is considered to study the effects on the KDFs of laminated composite cylindrical shells. A parametric study is performed on a set of shells, to demonstrate the impact of dimple depth and delamination area on the KDFs. The sensitivity of KDFs is also highlighted concerning the laminate stacking sequence.