<p>The effect of Ni content on the hydrogen embrittlement (HE) susceptibility of strain-hardened 316L stainless steel was examined using alloys containing 10, 12.5, and 14&#xa0;wt.% Ni. XRD and EBSD were used to characterize the microstructure, and SSRT tests were conducted in air and under in situ hydrogen charging. The results showed that, with increasing Ni content, the average grain size and SFE increased, whereas the deformation-induced martensite fraction decreased. The 12.5Ni and 14Ni specimens exhibited lower strength than the 10Ni specimen under both testing conditions. Compared with the air condition, in situ hydrogen charging increased the strength but reduced the ductility of all specimens. The 10Ni specimen exhibited the highest HE susceptibility, whereas the 12.5Ni and 14Ni specimens showed lower HE susceptibility. Fracture morphology indicated more pronounced hydrogen-assisted embrittlement in the 10Ni specimen, while the 12.5Ni and 14Ni specimens retained more ductile fracture features. The lower HE susceptibility of the 12.5Ni and 14Ni specimens is associated with their higher SFE and enhanced austenite stability. These factors suppress deformation-induced <i>α</i>^′-martensitic transformation and reduce the amount of <i>α</i>^′-martensite. Since <i>α</i>^′-martensite can act as a preferential site for hydrogen accumulation and hydrogen-assisted damage, a lower <i>α</i>^′-martensite fraction reduces the tendency for localized embrittlement and crack initiation during hydrogen-charged deformation.</p>