NbWTi refractory multi-principal element alloy has been synthesized using powder metallurgy route. 40 h of mechanical milling resulted in a single-phase alloy and subsequent spark plasma sintering transformed it into a multi-phase structure (1 BCC and 2 FCC phases). The alloy demonstrated an extremely high hardness of 12.29 ± 0.05 GPa at a load of 1000 g, along with excellent “density-normalized” hardness and indentation size effect. An indentation fracture toughness of 6.81 ± 0.16 MPa.m1/2 was measured using the cracks generated. Ultra-high absolute hardness, high “density-normalized” hardness and associated fracture toughness signifies the potential of this alloy for next generation structural engineering applications.