Cu0-mediated surface-initiated atom transfer radical polymerization (Cu0 SI-ATRP) is a highly versatile, oxygen-tolerant, and extremely controlled polymer-grafting technique that enables the modification of flat inorganic surfaces, as well as porous organic and polymeric supports of different compositions. Exploiting the intimate contact between a copper plate, acting as a source of catalyst and reducing agent, and an initiator-bearing support, Cu0 SI-ATRP enables the rapid growth of biopassive, lubricious brushes from large flat surfaces, as well as from various organic supports, including cellulose fibers and elastomers, using microliter volumes of reaction mixtures, and without the need for deoxygenation of reaction mixtures or an inert atmosphere. Thanks to a detailed analysis of its mechanism and the parameters governing the polymerization process, polymer brush growth by Cu0 SI-ATRP can be precisely modulated and adapted to be applied to morphologically and chemically different substrates, setting up the basis for translating SI-ATRP methods from academic studies into technologically relevant surface-modification approaches.