The current work is focused to investigate the synergetic interactions between biomass (groundnut shell, bagasse, rice husk, Prosopis juliflora, mixed wood sawdust) and hydro-rich plastics (Low-density polyethylene (LDPE) and Polyisoprene (PIP)) in microwave co-pyrolysis. The heating value of co-pyrolysis oil (38–42 MJ kg−1) was enhanced dramatically compared to biomass pyrolysis oil (20–28 MJ kg−1). Among biomasses studied, the energy yield of bio-oil obtained from rice husk with LDPE mixture is higher (42%). Whereas bio-oil from polyisoprene and groundnut shell mixture has the highest energy yield (78%). Each gram of co-pyrolysis feedstock consumed 12–18 kJ of incident microwave energy. An increase in overall energy efficiency in co-pyrolysis (62–70%) is observed compared to that of biomass pyrolysis (46–57%). Actual mass yield (31–47 wt%) of co-pyrolysis bio-crude is lower than its predicted value (42–57 wt%) due to the formation of lighter gases. In the combinations of and hydrogen-rich plastics considered in this study, it was found that co-pyrolysis of LDPE: bagasse has produced bio-crude with the highest yield of aliphatic hydrocarbons (25.78%), and co-pyrolysis of LDPE: rice husk has produced bio-crude with high selectivity of aromatics (11.7%). The extent of de-oxygenation was promoted in the co-pyrolysis due to synergy. © 2021 Elsevier Ltd