NiCuZn ferrite–(Ba_0.7Sr_0.3)TiO₃ (BST) composite ceramics with the BST content of up to 50 vol % were fabricated by sintering compacted powder mixtures at 900°C. The granulation of the BST powder and addition of a Bi₂O₃-based oxide additive effectively assisted the densification of the composite samples. The samples thus fabricated showed required ε_r values whereas their μ_r values were considerably reduced, especially for those with lower BST contents. From the detailed examinations on the effect of the Bi₂O₃-based oxide additives and on the process modification to improve the reduced μ_r values, the addition of a Bi₂O₃–ZnO additive with the eutectic composition of as low as 1 wt % was enough to produce a densified 10 vol % BST composite sample with a highest μ_r value. It was also found that the incorporation of ferrite granules calcined at 600°C caused further improvement of μ_r. Thus, a densified 10BST composite sample with μ_r = 125 was fabricated by low-temperature sintering at 900°C.