The nonlinear optical (NLO) and optical limiting (OL) properties of three new structures of organic NLO guest–host Poly(N-vinylcarbozole)/disperse orange 3 (PVK/DO3), PVK/disperse orange 13 (PVK/DO13), and PVK/disperse orange 25 (PVK/DO25) as a solution at different concentrations and as a thin-film sample are studied using continuous wave z-scan system at 532 nm. The open-aperture z-scan data of the NLO materials in the solution and thin-film samples displayed two-photon and saturable absorptions, respectively. The PVK/DO13 exhibites the largest and best values of the nonlinearities, such as n2, \beta, (3), compared with those of PVK/DO3 and PVK/DO25. This nonlinearity increases as the concentration increases. The results indicate that these NLO materials are good candidates for optical switching and OL devices.