The present work investigated the effect of hydrogen charging on the hydrogen embrittlement of carbide-free nanostructured bainitic steel using an electrochemical charging method with varying current density and charging duration. An austempering process was adopted for the development of nanostructured bainitic steel which mainly contains bainitic ferrite (BF) and retained austenite (RA). However, the volume fraction of BF and RA varies with the austempering temperature (250℃ and 300℃). The effect of hydrogen charging on the mechanical properties of nano-bainitic steel was examined by means of tensile tests and compared with the uncharged one. Optical microscopy and scanning electron microscopy (SEM) were used to study crack formation and propagation within the steel. It was observed that hydrogen charging reduced the ductility of the nano-bainitic steel, indicating a pronounced influence of hydrogen on its mechanical properties. SEM analysis of fractured surfaces demonstrated that hydrogen charging induced a transition from ductile to brittle failure in the nano-bainitic steel. In addition, hydrogen embrittlement was significantly affected by varying the fractions of BF and RA of the nano-bainitic steel.