In the present work, we report the fabrication, spectroscopic and mechanical properties of the novel f-MWCNTS/g-C3N4/TiO2 (MGT-NCs) metal-free ternary nanocomposite reinforced denture base PMMA. The functionalised-MWCNTs were introduced into the graphitic carbon nitride (g-C3N4) nanopowders (NPs). The obtained high porous f-MWCNTS/g-C3N4 NPs were mixed with 10 wt. % of TiO2 NPs previously hydrothermally synthesised. These prepared powders were characterized by XRD, FE-SEM, HR-TEM, FT-IR, and Raman spectroscopy to study the crystal structure and morphology. Using a mechanical blender 2 wt. % of g-C3N4, MWCNT/g-C3N4, and MGT-NCs were sintered into PMMA heat-activated denture base polymer powder and mixed with monomer to fabricate the composites through heat curing. Three different varieties of composites specimens were prepared into flexural, impact, compression, and hardness testing standards. From the comparative assessment of results, it is found that novel MGT-NCs reinforced PMMA exhibited superior mechanical properties. The surface morphology of the fractured and compressed specimens was studied using the SEM analysis and found to have dimples and increased roughness compared to the pristine PMMA and g-C3N4, MWCNT/g-C3N4. Hence, the fabricated novel metal-free MGT-NCs can be used as a reinforcement material in PMMA denture bases to achieve a concurrent enhancement in both physical and mechanical properties.