A novel energetic polynorbornene with pendant bisazidoacetyloxymethyl (named PNBAA) was designed, by combining its intrinsic energetic properties, potential good mechanical properties, its compatibility with a plasticizer and odourless polynorbornene in one polymer. A green synthesis of PNBAA was achieved starting from easily available materials, by using the solvent-free Diels–Alder reaction, chloroacetylation of norbornene dimethanol in water, solvent-free ring opening metathesis polymerization (ROMP), azidation in aqueous 3-pentanone and tandem ROMP and azidation in one pot. In addition, the Nuclear Magnetic Resonance (NMR) technique was utilized to investigate the key ROMP and azidation steps in situ. PNBAA as an energetic polymer was demonstrated by measuring its TG-IR, DSC and mechanical sensitivity. The strategy reported in this paper will lead to the general green synthesis of diverse energetic polymers in the future.