Thiol-yne click chemistry is demonstrated as a modular platform for rapid and practical fabrication of highly functional, multicomponent surfaces under ambient conditions. The principle is illustrated using a postmodification strategy in which poly(propargyl methacrylate) brushes were generated via surface-initiated photopolymerization and sequentially functionalized using the radical-mediated thiol-yne reaction. Brush surfaces expressing a three-dimensional configuration of "yne" functionalities were modified with high efficiency and short reaction times using a library of commercially available thiols, including functional thiols that demonstrate applicability for pH responsive surfaces and for bioconjugation. Sequential thiol-yne reactions in conjunction with simple UV photolithography were also applied to afford micropatterned, multicomponent surfaces. The practicality of the platform was further demonstrated by carrying out thiol-yne surface reactions in sunlight, suggesting the possibility of large scale modifications using renewable energy resources. Considering the mild reaction conditions, rapid throughput, and compatibility with orthogonal chemistries, we expect this platform to find widespread use among the materials science community.