On Aug 25, 2018, a G3-class geomagnetic storm, driven by a slow coronal mass ejection from the Sun, impacted the Earth’s magnetosphere causing a transient rearrangement of the charged-particle environment around the planet, which was clearly detected by the entire suite of detectors on board the CSES-01 satellite. In this work, a systematic characterization of the magnetospheric response to the disturbance is reported on the base of complementary electron-flux measurements from the high-energy particle detectors (HEPP-L/H, and HEPD) embarked on CSES-01. CSES-01 results are compared to homologous data from active ground-based and in-orbit instrumentation, and assessed to fit established scenarios in mainstream space-weather scientific literature.