Magnetization and magnetocaloric effect (MCE) of as-cast Gd-based bulk metallic glass (BMG) Gd24Er32Co24Al20 and the crystallized samples were investigated. Reentrant-spin-glass-like behavior was observed in the as-cast sample. With increasing degree of crystallization, the magnetic frustration increased, which could be seen from the increased divergence of the zero-field-cooled and field-cooled magnetization behavior (i.e., the spin-glass-like freezing behavior). The Curie temperature and magnetization decreased after crystallization. The as-cast BMG showed a large maximum magnetic entropy change (− ΔSm) of 9.9 (J kg−1 K−1) under a field change of 5 T, which was comparable with that of Gd metal and other Gd-based metallic glasses. The maximum − ΔSm reduced to 6.7 (J kg−1 K−1) after crystallization, which was still superior to the Fe-/Co-based amorphous alloys. Their good MCE combining with high electrical resistivity, outstanding mechanical properties, tunable nature, and sufficiently soft magnetic property makes them to be attractive candidate for magnetic refrigerants in the low-temperature range.