Electrospinning provides a versatile method for generating fibrous materials from a large variety of substances, including polymers, composites, proteins, and nano/microcolloids. In particular, the incorporation of nano/microparticles with polymeric materials is beneficial to many of electrospun fibers Ivith multiple functionalities. This report evaluates the spinnability of a polymer solution containing polymer nanoparticles obtained through electrospinning. Tunable structures of electrospun composite fibers were obtained from a blended solution of polyvinyl alcohol (PVA) and polystyrene nanospheres (PSNs). The in-fiber arrangements of polymer nanoparticle fibers, influenced by the PVA:PSN weight ratio, and the viscosity of the blended solution and the size of PSNs were systemically studied. Once PVA was determined to dominate the solution, the diameter of the electrospun PVA fibers was comparable to the diameters of the colloidal particles, which confined the nanospheres into string-on-bead and necklace-like structures. When PSNs occupied a large portion of the solution, PVA wrapped the PSNs, forming a blackberry-like aggregate and a uniform colloidal fiber. The results from the colloid electrospinning serve as references in the creation of novel composite fibers involving various polymer nanoparticles via elec-trospinning. The obtained composite fibers of the polymers and colloids are expected to have potential application in various areas.