•26 ferritic stainless steel beam-column tests undertaken.•Over 2000 numerical results generated for austenitic, duplex and ferritic stainless steel CHS beam-columns over a range of local and global slenderness values.•Existing Eurocode 3 design provisions are evaluated and new design proposals are determined and verified.•Reliability analyses are undertaken for existing and proposed stainless steel CHS beam-column design methods using the new experimental and numerical dataset. The present work was prompted by shortcomings identified in existing design provisions for stainless steel circular hollow section (CHS) beam-columns. First, addressing a lack of existing experimental data, a series of ferritic stainless steel CHS beam-column tests was undertaken at the cross-section and member levels. In total, 26 beam-column tests, including two section sizes (a non-slender class 3 and slender class 4 cross-section), two member slenderness values for each cross-section type and a wide range of loading eccentricities were carried out to investigate the interaction between local and global buckling. Following validation of finite element (FE) models, a numerical study was then undertaken to explore the buckling response of stainless steel CHS beam-columns, covering austenitic, duplex and ferritic grades with a wide range of local and global slendernesses and applied loading eccentricities. Over 2000 numerical results were generated and used to assess new design proposals for stainless steel beam-columns, featuring improved compression and bending end points and new interaction factors. The new proposals are more consistent and more accurate in their resistance predictions than the current EN 1993-1-4 (2015) design approach. The reliability of the new proposals has been verified by means of statistical analyses according to EN 1990 (2005).