Display omitted •La(Fe,Si)13/La70Co30 were fabricated by low temperature hot-pressing followed by annealing.•With increasing La70Co30 up to 16 wt%, the (σbc)max improved dramatically from 63 to 352 MPa.•Co atoms from La70Co30 alloy diffused into the 1:13 phase, increasing the TC of the composites.•The MCE of these composites can be adjusted by increasing La70Co30 and prolonging annealing time. Magnetocaloric composites La(Fe,Si)13/La70Co30 were fabricated by hot-pressing (HP) followed by annealing. With increasing La70Co30 binder content up to 16 wt%, the maximum compressive strength (σbc)max improved dramatically from 63 to 352 MPa. However, the maximum magnetic entropy change (–ΔSM)max decreased from 10.0 to 5.6 Jkg–1K−1 because of the presence of non-magnetic La70Co30. After annealing at 1323 K for 4 h the (σbc)max of HP + Annealed composites with up to 12 wt% La70Co30 doubled compared to HP samples. On the other hand, for a La70Co30 content of 16 wt%, the (σbc)max of HP + Annealed composites decreased slightly compared to that of HP samples, due to reduced α-Fe content and much greater 1:13 phase content in HP + Annealed samples. Remarkably, the (–ΔSM)max of HP + Annealed composites improved from 4.8 to 9.2 Jkg–1K−1 (under 2 T), due to 1:13 phase recombination, after annealing at 1323 K for 4 h.