Non-isothermal and isothermal oxidation behavior of four Zr-based bulk metallic glasses (Zr58Cu22Co4Ag4Al12, Zr58Cu22Co2Ag6Al12, Zr58Cu22Fe4Ag4Al12, and Zr58Cu22Fe2Ag6Al12 (compositions are in at.%)) has been studied in oxygen environment. Non-isothermal oxidation has been performed at different heating rates up to 1,173 K to understand the effect of progressive crystallization on the oxidation behavior. In addition, crystallization behavior of the glassy alloys has been studied, and activation energies have been calculated in an inert and oxygen environment. Partial replacement of iron with silver and cobalt has a distinct effect on the oxidation and crystallization behavior of the alloys. Oxidation of the glassy alloys starts with the dissolution of oxygen in the amorphous matrix followed by rapid oxidation after crystallization.