A significant challenge for greater utilization of zeolitic imidazolate frameworks (ZIFs) is creating a synthesis method to produce these materials with uniform, nanometer-scale particle size, and high surface areas while achieving high yields. We demonstrate a novel method to produce ZIF-8 nanoparticles with uniform diameters in the range of 60-80 nm involving a jet-mixing reactor. While ZIF nanoparticle synthesis typically involves using excess ligand, the jet-mixing reactor can be operated at ambient conditions using preferred solvents and stoichiometric quantities of ligand and metal (i.e., ligand:metal of 2:1) with yields as high as 89%. The jet-mixing reactor is studied to determine the effect of different synthesis parameters including ligand to metal ratio, base concentration, solvent, and mixing intensity. The base concentration has the most effect on the product size, morphology, and yield. Furthermore, we demonstrate that the jet-mixing method can be scaled to increase productivity by designing, constructing, and testing a larger reactor.