Polymers have dominated over most of the materials in a plethora of applications. In several cases, the need to modify the surface properties of the polymer (selectively) arises. Plasma is considered to be the best tool to modify polymeric surfaces homogeneously due to the versatility of the effects that different plasmas have on polymeric surfaces in terms of chemistry and topography, along with the fact that there is no demand for further specialty equipment or additional steps. This entry describes in general terms how the low-pressure plasma treatments influence polymer surfaces and lists the main advantages and disadvantages. Subsequently, the most remarkable applications of low-pressure plasma-treated polymers are presented according to the research published over the years. Microfluidic devices, antireflective surfaces, smart materials and composites, and biochemical and biological applications are highlighted with a focus on advances and trends in their research field.