Plasma and ultraviolet (UV) polymerizations are widely used techniques for biomaterial surface modification (e.g., application of coatings), and the latter is also used for the development of new biomaterials. These techniques allow the functionalization of the material enabling it to perform specific functions and improve its performances. This produces highly performant biomaterials with superior properties which are used in various biomedical applications. Nitrogen-based functionalities such as primary amines are particularly important as they yield better cell–material interactions. This entry discusses amine biomaterial functionalization via plasma and UV polymerizations focusing on their use in tissue engineering and explains the differences between the two processes. Surface characterization techniques such as water contact angle (WCA) measurements, Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), spectrophotometry (SPE), scanning electron microscopy (SEM), atomic force microscopy (AFM), and optical reflectance spectroscopy (OPS) will also be discussed. This entry thereby provides a comprehensive review of the modification and development of highly performant biomaterials by amine functionalization through plasma and UV polymerization techniques.