Applying optimisation techniques to the design of cold-formed steel (CFS) sections can lead to more economical and efficient design solutions. However, a crucial factor in such an optimisation is to arrive at a solution which is practical and fits within the constraints of the fabrication and construction industries. Targeting this objective, a comprehensive investigation was conducted on the practical optimisation of CFS beams using a Particle Swarm Optimisation (PSO) method. Six different CFS channel section prototypes were selected and then optimised with respect to their flexural strength, determined according to the effective width based provisions of Eurocode 3 (EC3) part 1–3. Comparing the capacities of the optimised sections to those of the original channel sections with the same amount of structural material, significant improvements were obtained. The accuracy of the optimisation procedure was assessed using experimentally validated nonlinear Finite Element (FE) analyses accounting for the effect of imperfections. The results indicated that, using the same amount of material, the optimum sections offered up to 25% and 75% more flexural strength for laterally braced and unbraced CFS beams, respectively, while they also satisfied predefined manufacturing and design constraints. Therefore, the proposed optimisation methodology has the potential to prove useful in practical design applications.