jats:titleAbstract</jats:title> jats:pA robust and reliable jats:italicin-situ</jats:italic> magnetization method is essential for exploiting the outstanding magnetic flux trapping ability of bulk superconductors in practical applications. We report a 4.8 T peak trapped magnetic field, jats:italicB</jats:italic> jats:subT</jats:sub>, achieved at 30 K in a 36 mm diameter GdBajats:sub2</jats:sub>Cujats:sub3</jats:sub>Ojats:sub7-jats:italicδ</jats:italic> </jats:sub>–Ag bulk superconductor using pulsed field magnetization (PFM). To realize this, we have developed a reliable two-step multi-pulse PFM process based on understanding and exploiting the avalanche-like flux jump phenomenon observed in these materials. The magnitude of the applied pulsed magnetic field (jats:italicB</jats:italic> jats:suba</jats:sub>) necessary to trap 4.8 T was merely 5.29 T, corresponding to a remarkable magnetization efficiency (jats:italicB</jats:italic> jats:subT</jats:sub>/jats:italicB</jats:italic> jats:suba</jats:sub>) of 90%.</jats:p>