Fe76-xB7C7P7Si3Mox (x = 0, 1, 2, 3, 4 and 5) bulk metallic glasses (BMGs) were designed and successfully prepared. The effects of Mo content on the glass forming ability (GFA), thermal stability, crystallization behavior, soft magnetic properties, and mechanical properties have been investigated. It was found that the appropriate replacement of Fe by Mo could improve the GFA of the Fe-based alloys, and the critical size could reach 2.5 mm for the alloy with 3 at.% Mo. The crystallization behavior of glassy alloys indicates that the competition between the metastable phase and alpha-Fe, Fe3(B, P) phases results in the change of GFA. Furthermore, the metallic glasses possess superior comprehensive properties with high saturation magnetization of 1.04-1.50 T, low coercivity of 0.9-3.5 A/m, high fracture strength of 3240-3565 MPa, and improved plasticity up to 0.9-1.5 %.