Low plasticity is a key drawback limiting the widespread use of bulk metallic glasses. Although heat treatment and thermo-mechanical processing techniques are not applied to metallic glasses (only to supercooled liquids), since heating leads to embrittlement either due to structural relaxation or thermal crystallization, in this paper, we demonstrate a strong positive effect of cold rolling and subsequent thermal annealing below the glass-transition temperature on room-temperature mechanical properties of a Zr62·5Cu22·5Fe5Al10 glassy alloy. As a result we observed mechanical softening and appearance of tensile ductility (up to 1.5%) in bulk samples and an increase in hardness by up to 25% in ribbon samples yet retaining good bending plasticity. We believe that the proposed method can be applied to a number of metallic glasses. Display omitted •Nanoscale (∼7 nm) glassy particles in a metallic glassy phase.•Supreme mechanical properties of these materials.•Solid state thermo-mechanical processing below the glass-transition temperature.•Tensile ductility (up to 1.5%) in bulk samples.•hardening without embrittlement in ribbon samples.