Present investigation deals with formulation and evaluation of tamoxifen (TMX)-loaded liquid crystalline nanoparticles (TMX-LCNPs) for improving oral bioavailability and safety of the existing treatment. Hexagonal Glyceryl monooleate-based TMX-LCNPs (GLCNPs) and Phytantriol-based TMX-LCNPs (PLCNPs) were prepared by dilution-through-hydrotrope method for oral administration. Oleic acid was incorporated in the lipid matrix to enhance the drug loading in the LCNPs. Optimized LCNPs displayed small particle size with a narrow distribution, sustained drug release and high gastrointestinal stability. TMX-LCNPs were found to be considerably higher cytotoxic to MCF-7 cells as compared to free TMX. Substantial fold enhancement in oral bioavailability (~7- and ~5-folds with TMX-GLCNPs and TMX-PLCNPs, respectively) was evident followed by significant reduction in tumor burden with lesser hepatotoxicity. Out of the two LCNP formulations, PLCNPs were found to be better in convalescing the disease.