Geometrically-confined hollow cathode plasma discharges, also known as microplasmas, have received considerable attention in recent years because of their non-equilibrium, high-pressure operating characteristics (e.g., Telectron >> Tion, Tneutral and high collision frequencies) are ideally suited for applications such as UV radiation sources, toxic gas remediation, O3 generation, and synthesis of aerosolized nanoparticles. However, microplasmas have not been exploited for thin film deposition, and very little is currently known about the plasma physics and fluid mechanics involved in flow-through jet type cathode geometries as well as how microplasma jet operation ultimately affects spray deposition processes. This dissertation focuses on the design, characterization, and use of capillary and slit-type flow-through microplasma jets for nanoparticle synthesis (Cu, Pd, Ni) and deposition of nanostructured metal (Cu, Ni) and metal oxide (CuO, PdO, NiO, Fe2O3, SnO2) thin films on a variety of surfaces. Microplasma operation (IV characteristics, supersonic flow dynamics, and excited state species) and its influence on material deposition processes (transport effects, flux uniformity, ballistic aggregation vs. diffusional phenomena, and film morphology) were studied in detail. Overall, this work demonstrates that microplasma-based deposition is a novel and general route to realize a variety of nanostructured thin film materials for applications in (photo-electro)catalysis, solar energy harvesting, chemical sensing, and opto-microelectronics.