Nanocapsules (NCs) are submicron-sized core shell systems which present important advantages such as improvement of drug efficacy and bioavailability, prevention of drug degradation, and provision of controlled-release delivery. The available methods for NC production require expensive recovery and purification steps which compromised the morphology of NCs. Industrial applications of NCs have been avoided due to the aforementioned issues. In this study, we developed a new method based on a modified self-microemulsifying drug delivery system (SMEDDS) for in situ NCs production within the gastrointestinal tract. This new methodology does not require purification and recovery steps and can preserve the morphology and the functionality of NCs. The in situ formed NCs of Eudragit RL PO were compared with nanospheres (NEs) in order to obtain evidence of their core-shell structure. NCs presented a spherical morphology with a size of 126.2 ± 13.1 nm, an ibuprofen encapsulation efficiency of 31.3% and a zeta-potential of 37.4 mV. Additionally, NC density and release profile (zero order) showed physical evidence of the feasibility of NCs in situ creation.