<p>Bipolar plates (BPs) are crucial components of proton exchange membrane fuel cells (PEMFCs), which provide electrical conductivity, structural integrity, and play a critical role for gas distribution and water management. However, the preparation of low-cost BPs with mutually enhanced electrical conductivity, mechanical strength, and electrochemical durability remains challenging. The present work highlights the utilization of locally sourced, highly graphitized and pure flake shaped natural graphite as a sustainable filler for the development of BPs on a commercial scale, with the required set of characteristics. It functions as an effective natural conductive filler compared to expensive and synthetically produced carbon-based fillers used in literature, involving complex and overdependence on energy-intensive routes. In this study, composites with different natural graphite particle sizes and recyclable polyphenylene sulfide (PPS) have been prepared via ball milling and compression molding process. Comparatively, from twelve different compositions, the composite with a combination of 10 wt% fine graphite, 60 wt% jumbo graphite and 30 wt% PPS demonstrates a synergistic enhancement of electrical/thermal conductivity, thermal stability, and compressive strength. The prepared composite demonstrates a higher degree of crystallinity, high gas (N₂) impermeability, and the lowest thermal expansion. The hybrid particle size formulation has the potential to develop natural graphite-based composite BPs with simultaneously improved multifunctional properties, above DOE. This study provides valuable insights to develop natural graphite-based composite BPs through an industrially viable processing approach, for future PEM fuel cell applications.</p>