Abstract: Tungsten (W) powder and 1.0% (mass fraction) high-entropy boride ceramic (TiZrHfNbMo)B2 powder were used as raw materials to fabricate a W alloy via mechanical ball milling and spark plasma sintering. Microstructural characterization and mechanical testing revealed that, during sintering, (TiZrHfNbMo)B2 reacted in situ with oxygen impurities to form high-entropy (TiZrHfNbMo)O2 particles with a TiO2-II crystal structure. The sintered W alloy exhibited a fine equiaxed grain structure with an average grain size of 2.02 μm, and most of the (TiZrHfNbMo)O2 particles were uniformly distributed within the W grains, with an average size of approximately 65?nm. The alloy achieved a relative density of 98.8% and a Vickers hardness of 489 HV. At 600?℃, the alloy exhibited an ultimate tensile strength of 613 MPa together with a total elongation of 17%. Transmission electron microscopy revealed pronounced dislocation bending and entanglement around the dispersed nanoparticles, indicating their strong interaction with moving dislocations. The enhanced mechanical performance is attributed to the synergistic effects of oxygen scavenging through the in situ solid-state reaction, grain refinement, and dispersion strengthening introduced by intragranular nanoscale oxide particles.