Dispersion strengthening improves mechanical properties and wear resistance of alloys, yet optimizing plasticity in ceramic-reinforced systems faces challenges in particle-matrix compatibility and fundamental strengthening mechanisms. This study systematically investigates CoCrFeNi(SiO 2) 0.1/(B 4C) 0.1 high-entropy alloy (HEA) compositions fabricated using mechanical alloying (MA) and spark plasma sintering (SPS). Phase analysis reveals that the MA powders contain a dual-phase structure comprising body centered cubic (BCC) and face centered cubic (FCC) phases, along with limited metallic inclusions. Subsequent SPS processing induces a complete BCC-to-FCC phase transformation in the consolidated HEA matrix, suggesting significant thermal stability differences between the constituent phases. The baseline CoCrFeNi HEA shows dual-phase structure composed of FCC matrix and Cr-enriched oxide. Addition of SiO 2 ceramic particle induces multiphase reorganization, yielding FCC matrix, Cr-rich oxide/carbide and Si-C-O-rich compound with two-dimensional graphene-like structure. Further modification with little B 4C produces a refined microstructure featuring ultrafine FCC grains and dispersed ultrafine/nano Cr-Si-O or Cr-B-O compounds and two-dimensional graphene-like Si-C-O hybrids nanosheet. The SiO 2/B 4C hybrid reinforcement elevates compressive yield strength (~90% and 45% increase), nano-hardness (~2.3 and 1.7   GPa increase). Quantitative analysis of precipitation strengthening and fine grain strengthening increments elucidates the effects of SiO 2/B 4C addition on HEAs. The established structure with property relationships guide ceramic reinforced HEA design for tailored performance, expanding advanced structural applications.