The potential of using Albizia amara plant extract to synthesize environmentally-friendly Mn3O4, Nd2O3 nanoparticles (NPs) and NdMn2O5 nanocomposites (NCs) for supercapacitor applications was explored. Various techniques will be used to characterize the resulting nanocomposite and evaluate its electrical properties and electrochemical performance. The study will also investigate the impact of synthesis parameters on the nanocomposite properties and optimize them for enhanced supercapacitor performance. Additionally, the environmental sustainability of using Albizia amara plant extract as a green reducing agent will be assessed. The study found that NdMn2O5 nanocomposites possess 754 F/g specific capacitance at 0.5 A/g and concluded superior electrode material properties for supercapacitors compared to the Mn3O4 and Nd2O3 nanoparticles. Moreover, hybrid supercapacitor is employed in as-prepared NdMn2O5 as positive electrode and activated carbon as negative electrode. Assembled hybrid NdMn2O5//AC exhibits 42 Wh/kg specific energy and 379 W/kg power density. 94.34 % of coulombic efficiency and 76.11 % of capacitance retention was perpetuating after 15,000 cycles. The use of Albizia amara plant extract shows promise as green alternative, cost-effective and environmentally-friendly methods for synthesizing NdMn2O5 nanocomposites for energy storage devices.