The purpose of the current study was to improve the solubility of ibuprofen, a poorly water-soluble drug, in a microemulsion system that is suitable for oral administration. Microemulsion was prepared using different sorts of oils, surfactants, and co-surfactants. Pseudo-ternary phase diagrams were used to evaluate the microemulsion domain. The formulations were characterized by solubility of the drug in the vehicle, droplet size, and drug release. The optimal formulation consists of 17% Labrafil M 1944CS, 28% Cremophor RH40/Transcutol P (3:1, w/w), and 55% water, with a maximum solubility of ibuprofen up to 60.3 mg/ml. The mean droplet size of microemulsion was 57 nm. The pharmacokinetic study of microemulsion was performed in rats and compared with granule formulation. The microemulsion has significantly increased the C(max) and area under the curve (AUC) compared to that of the granule (p < 0.05). The relative bioavailability of ibuprofen in microemulsions was 1.9-fold higher than that of the granule. These results indicated that this novel microemulsion is a useful formulation for enhancing the oral bioavailability of ibuprofen.