Na3MnCO3PO4 (NMCP) particles were synthesized via ball milling of Mn(NO3)2.4H2O, Na2HPO4.2H2O and Na2CO3.H2O powders. The particles were anchored onto reduced graphene oxide (rGO) sheets during hydrothermal reduction process under stirring. Materials produced were characterized by x-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), thermogravimetric (TG) measurement and galvanostatic charge/discharge tests. Results showed that dissolution of ball milling products in DI water is an effective method for separation of NMCP from byproducts. Best milling time for production of pure NMCP of minimum particle aggregation was 60min. After preparing the composite, the needle-like NMCP particles of ∼15 nm diameter were anchored onto rGO sheets. As a promising cathode candidate for Na-ion batteries, NMCP and NMCP/rGO electrodes displayed initial capacities of 103 and 141mAhg−1 at C/30 rate with capacity retention of 71% and 81% after 15 cycles, respectively. Improvement of the cycling performance at higher rates attributed mainly to the extremely fine NMCP nanoparticles and their almost uniform distribution on rGO conducting network which resulted in electronic and ionic conductivity enhancement and therefore improved the reversibility of intercalation/deintercalation reactions.