This paper presents an experimental and numerical investigation on stainless steel I-beams with sinusoidal corrugated webs. To characterise the shear resistance and failure mechanism, nine full-scale specimens fabricated from austenitic stainless steel (grade 1.4301) were subjected to three-point bending loading condition. The experimental results showed that at low slenderness ratios, the web could exceed its nominal yield strength. At the ultimate load level, initial local buckling occurred in a single corrugation wave. As the load increased further, the local buckling spread to the other waves as well and the post-buckling failure mode resembled global buckling. Based on the results of the experimental tests, advanced finite element models were developed and validated to conduct a comprehensive parametric study. The numerical analysis demonstrated that the shear buckling capacity of stainless steel girders with sinusoidal corrugated web exceeds the predictions of EN 1993–1–5:2006. On this basis, analytical expressions are proposed to account for the increased ultimate shear resistance. In addition, the accuracy of existing expressions for determining the elastic critical local shear buckling stress is evaluated, and a new formula is proposed. Statistical analysis shows that the proposed expressions provide improved accuracy within the investigated parameter ranges.