This work is devoted to highlight some peculiar aspects of the chemical and physical behavior of the well-known 1-butyl-3-methylimidazolium (bmim⁺) tetrafluoroborate (BF₄⁻) (bmimBF₄) ionic liquid (IL) in water (W) and in the presence of the anionic surfactant sodium bis(2-ethylhexyl) sulfosuccinate (NaAOT) basically through the evaluation of the self-diffusion coefficients of the various chemical species in solution via PGSTE-NMR experiments. The amphiphilic nature of bmimBF₄ was demonstrated investigating the W/bmimBF₄ binary phase diagram. The analysis of the collected data revealed that the ion-pair dissociation is a progressive process. More importantly, W molecules and bmimBF₄ ions diffuse within different domains, strongly suggesting that the system under investigation is actually nanostructured. The imidazolium-based IL's peculiar amphiphilic features are deduced from the phase behavior alteration caused upon the addition of NaAOT to the W/IL system, and the differences promoted by exchanging the BF₄⁻ counterion with Br⁻. NaAOT in W forms a lamellar liquid crystalline (LC) phase that, with increasing concentration, forms a bicontinuous cubic LC phase and then a reverse hexagonal LC phase (Rogers, J.; Winsor, P. A., Nature 1967, 216, 477–479). By the addition of oil, NaAOT forms water-in-oil microemulsion (De, T. K.; Maitra, A., Adv. Colloid Interface Sci. 1995, 59, 95–193). NaAOT, therefore, can establish flat or negative curvature of the polar–apolar interface. Dramatic effects are observed as a result of the interaction between the aforementioned ILs and the anionic surfactant. The mixed systems may produce micelles having positive curvature, whereas the system AOT/W/bmimBr produces a bicontinuous micellar solution. The remarkable differences between the two systems arise from the specific counterion effect.