Abstract The glass-forming ability (GFA), the thermal stability and the crystallization behavior of Cu46Zr46Ag8 metallic glass and the thermal stability of the competing metastable B2 CuZr phase were investigated in order to fabricate the corresponding shape memory bulk metallic glass (BMG) composites based on a new prediction strategy. A rather large supercooled liquid region and a relatively low liquid fragility indicate a quite high thermal stability of the present glass. With the addition of Ag to Cu50Zr50 alloy, it becomes more difficult for the metastable B2 phase to decompose into the room-temperature equilibrium phases and to transform into martensitic phases during quenching. Based on these insights, a Cu46Zr46Ag8 BMG and its composites with different volume fractions of in situ precipitated B2 crystals were fabricated by carefully controlling the casting process. The BMG composites exhibit a larger plasticity and obvious work hardening compared to the monolithic BMG, which can be attributed to the formation of multiple shear bands and a deformation-induced martensitic transformation (MT) within the B2 crystals.