Polystyrene microspheres are widely used in biomedical applications due to their uniform size and surface properties. They serve as effective carriers in drug delivery systems, enabling controlled release and targeted therapy. These microspheres are also employed in diagnostic assays, such as immunoassays and flow cytometry, where they act as labels or standards for cell separation and detection.

In research and development, they are used as calibration standards for instruments like microscopes and particle counters because of their consistent spherical shape and narrow size distribution. Their surface can be modified with functional groups to bind antibodies, proteins, or DNA, making them valuable in biosensing and molecular imaging.

Polystyrene microspheres are also utilized in the cosmetics industry as bulking agents, viscosity controllers, and exfoliants in creams and lotions. In industrial applications, they function as spacers in electronic materials, additives in coatings for texture and gloss control, and tracers in fluid dynamics studies to visualize flow patterns.