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Wrapping of reduced graphene oxide (RGO) over 2D layered transition metal oxide cathode material is very prevailing strategy to improve the capacity and cycling performance of cathode materials for sodium-batteries. However, poorly dispersed RGO in aqueous medium restricts the proper attachment of active-material with RGO resulting in non-uniform wrapping. Herein, graphene oxide is functionalized non-covalently through multifunctional agent dextran and reduced moderately to dextran functionalized-RGO (Dx-RGO). Further, it is attached chemically with Na[Ni0.60Mn0.35Co0.05]O2 (NMC) nano-sphere, which is synthesized by co-precipitation method. Strategically, hydrothermal-treatment is applied to empower reduction as well as attachment of Dx-RGO with NMC nano-sphere to prepare NMC-Dx-RGO composite. The successful attachment of Dx-RGO over NMC nano-sphere is confirmed by various experimental techniques and their resulting electrochemical performances are investigated. The surface-modified NMC-Dx-RGO cathode material exhibits high discharge capacity of 151 mAh g−1 at 0.1C and 55% capacity retention after 120 cycles at 0.2C. Dx-RGO layer acts as conducting network around NMC providing uniform state of charge distribution (SOC), which facilitates fast transport of electrons. The presence of protective Dx-RGO layer suppresses the growth of resistive layer at cathode-electrolyte interface (Rcei) and prevents the dissolution of transition metals cathode material to get high discharge capacity for sodium-batteries.