Reverse atom transfer radical polymerization of methacrylonitrile (MAN) initiated by azobisisobutyronitrile (AIBN) was approached for the first time in the absence of any ligand in four novel ionic liquids, 1-methylimidazolium acetate ([mim][AT]), 1-methylimidazolium butyrate ([mim][BT]), 1-methylimidazolium caproate ([mim][CT]), and 1-methylimidazolium heptylate ([mim][HT]). The polymerization in [mim][AT] not only showed the best control of molecular weight and its distribution but also provided a more rapid reaction rate with the ratio of [MAN]:[FeCl3]:[AIBN] at 300:2:1. The block copolymer PMAN-b-PSt was obtained via a conventional ATRP process in [mim][AT] by using the resulting PMAN as a macroinitiator. After simple purification, [mim][AT] and FeCl3 could be easily recycled and reused and had no effect on the living nature of reverse atom transfer radical polymerization of MAN.