Development of metallic glasses is hindered by the difficulties in manufacturing bulk parts. We report on the preparation of glassy alloys using the spark plasma sintering of gas atomized powders. The Zr57Cu20Al10Ni8Ti5 alloy processed has a high glass forming ability. Densification is obtained at the glass transition temperature (390 °C) under high pressure (≈500 MPa). Systematic study of the effect of powder particles size and sintering time is performed through structural and thermal analyses. Local and partial devitrification of the amorphous alloy is detected, resulting from local temperature overshoots. From these analyses, an approach of the spark plasma sintering mechanism of metallic glasses is proposed.