Improved size monodispersity of populations of polymer nanospheres is of enormous interest in the fields of nanotechnology and nanomedicine. As such, the knowledge of exact experimental conditions for precise production of nanospheres is needed for non-aqueous systems. This work presents the use of a controlled microfluidic transport method to study the experimental parameters for fabricating nanoparticles utilizing phase inversion. We report two microfluidic methods for forming polymer nanospheres in small batches to determine the formation conditions. These conditions were then implemented to perform higher throughput formation of the polymer nanospheres of desired size. The controlled microfluidic environment in the laminar flow regime produces improved size monodispersity, decreased average diameter, and affords a greater degree of control over the nanosphere size distribution without adding surfactants or additional solvents. Experiments show a non-linear trend towards decreasing size with decreasing polymer concentration and a linear trend towards decreasing size with increasing flow rate indicating time-course-dependent nucleation and growth mechanism of formation for the resultant nanosphere population within the range of conditions tested.