Anisotropic particles, in shape or chemistry, have raised enthusiasm since they interact with their surrounding in unique ways, leading to complex assemblies that can be used in applications ranging from energy to health. In this study, two different types of polymeric nanoparticles, blend-type with two hydrophobic polymers and Janus type with hydrophobic and hydrophilic parts were produced thanks to an emulsification elongational-flow microprocess. Particles with controlled sizes and size distribution were successfully produced in one step and the effect of material (e.g. polymers’ composition and concentration, solvent) and process (e.g. flow rates, emulsification time) parameters on nanoparticles’ characteristics were thoroughly studied. Particles’ diameter ranged from 90 to 200 nm, depending on the aforementioned parameters.