The research study focuses on the structural behaviour of Cold-Formed Steel (CFS) built-up I section columns subjected to axial compression. Lipped channels connected back-to-back using self-drilling screws were tested under fixed-fixed boundary condition. Test parameters such as local slenderness, distortional slenderness, global slenderness, cross-section dimensions, intermediate spacing of the screws, and length of the column were investigated. The columns exhibited individual buckling modes (Local, Distortional) as well as interactive buckling modes (Local-Distortional, Local-Distortional-Global). The effect of intermediate screw spacing was predominant in the governing failure modes. The test results were compared with Direct Strength Method design equations of American Iron and Steel Institute design standard and its suitability was verified. Based on the findings of the test results, specific design guidelines for CFS built-up sections failing in interactive local-distortional buckling and local-distortional-global buckling are proposed.