Based on the surface properties of aqueous silica, boehmite, and SiC‐whisker dispersions, SiC‐whisker‐reinforced lithium aluminosilicate (LAS) matrix composites were fabricated by a mixed colloidal processing route. The composites were characterized by a uniform spatial distribution of SiC whiskers throughout the matrix. The fracture toughness increased from 1.3 MPa.m1/2for the LAS specimen to 5.0 MPa.m1/2for the hot‐pressed composite (950°C and 20 MPa for 20 min) containing 20 wt% SiC whisker. The increase in fracture toughness appears to result mainly from crack deflection and crack bridging by whiskers with some additional toughenings from load transfer and whisker