This study shows processing of CuZr-based bulk metallic glass (BMG) via severe plastic deformation (SPD) under extreme loading condition, and investigates the effects of SPD induced by high-pressure torsion (HPT) on microstructural, thermal and (thermo)mechanical properties of Cu46Zr46Al8 BMG. The influence of sub-Tg annealing and HPT treatment on the structure-property relationships of BMGs is assessed separately and alternately in reference to the as-cast state. High extent of applied shear strain during HPT generates free volume in the structure and has mechanical softening and structural rejuvenation effect against mechanical hardening and embrittlement of the glass induced by sub-Tg isothermal heat treatment (HT). Thermal properties, structural modifications, and surface morphology/compositional changes are investigated by differential scanning calorimetry, X-ray diffraction, and scanning/transmission electron microscopy, respectively. In general, this thesis aims for the enhancement of the intrinsic properties of CuZr-based BMGs via controlled nanocrystallization and their uniform distribution throughout the amorphous BMG matrix.