The purpose of this work is intended to investigate the potential of self-nanoemulsifying (SNE) drug delivery system for enhanced oral bioavailability of etoposide by P-glycoprotein (P-gp) modulation. The components of SNE formulation were optimized by their solubilization and emulsification efficiency. The ternary phase diagrams provided nanoemulsion existence ranges and the corresponding formulations were developed and evaluated via thermodynamic and dispersibility tests. The successful formulations were characterized for various parameters including time required for self-emulsification, percentage transmittance, droplet size, surface morphology, zeta potential and in vitro release. The etoposide loaded SNE9 formulation showed 2.6- and 11-fold higher permeability coefficient in apical to basolateral direction across Caco-2 monolayers as compared to the Etosid and plain drug solution, respectively. The etoposide loaded SNE9 formulation showed a higher cytotoxicity at the highest tested concentration compared to the blank SNE9 formulation and the free etoposide. Furthermore, an in vivo pharmacokinetic study of etoposide in SNE9 formulation showed 3.2- and 7.9-fold increase in relative oral bioavailability compared with that of etoposide in Etosid and drug suspension, respectively. Thus, the developed SNE drug delivery system could be a valuable tool for the effective oral delivery of etoposide.