molecular weight polymer (HMWP) based GPEs display superior ionic conductivity, good mechanical strength, and filming process ability. [4,5] HMWP, poly(methyl methacrylate) (PMMA) has been studied extensively as the polymer matrix of GPEs due to some attractive properties like non-toxicity, high ionic conductivity, good mechanical and chemical stability, and interfacial stability against lithium. [5-9] The various applications of PMMA confirm that the property of the polymer changes with its molecular weight. [10-14] Besides, the biocompatible nature of PMMA enhances its use as bone cement, where high molecular weight PMMA powder shows higher flexural properties. [15-17] Commonly, the high initiation efficiency and low extent of chain transfer and termination reactions are required in the synthesis of HMWPs. Because of rapid acceleration in the rate and formation of a network polymer, bulk polymerization techniques are mostly used for the synthesis of HMWPs even at low conversion. [18-20] PMMA can be synthesized from the methyl methacrylate (MMA) by using the numerous kinds of metal Here, one-step synthesis of high molecular weight poly(methyl methacrylate) (PMMA; 1000-1650 kg mol −1) is reported by using zeolitic imidazole framework-8 (ZIF-8) catalyst without any co-catalyst in the absence of a solvent. This type of high molecular weight PMMA has different applications, mainly in gel polymer electrolyte and bone cement. Zwitterionic type mechanism is proposed where the active acid site of the catalyst dominates for initiation of polymerization. Without any significance loss of structural morphology and catalytic activity, ZIF-8 can easily be recycled for further uses. ZIF-8 exhibits superior activities for the synthesis of high molecular weight PMMA compared to the heterogeneous catalysts mentioned earlier.