With the aim of synthesizing a new ferromagnetic CoFe-based glassy alloy with a large supercooled liquid region, we studied the (CoxFe1−x)62Nb8B30 (x=0–1) alloy system. The alloy corresponding to x=0.5 exhibits a large supercooled liquid region of 101K, together with a high fracture strength of approximately 5000MPa at room temperature and superplasticity near its glass transition temperature. In addition, the x=0.5 alloy as a soft magnetic material shows a low coercivity below 2A/m, a high effective permeability of about 20,000 at 1kHz and 3400 at 1MHz as well as a giant magnetoimpedance ratio of 62%. The combination of superplasticity and soft magnetic properties makes this alloy promising for future functional applications.