Thermoresponsive nanofibers by very fast grafting of N,N-isopropylacrylamide (NIPAAm) from electrospun atom transfer radical polymerization (ATRP) macroinitiator are presented in this work. The heterogenous grafting of NIPAAm onto macroinitiator fibers could be done in few minutes, i.e., in less than 5 min. The procedure involved electrospinning of an ATRP macroinitiator and subsequent PNIPAAm grafting using "grafting from" technique. The ATRP Macroinitiator was based on a copolymer of methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA). The growth of the PNIPAAm layer on electrospun fibers was followed by IR-spectroscopy and SEM analysis. The temperature-dependent-phase transition was proven by contact angle measurements and could be shown on the same surface for many cycles.