SummaryBuckling‐restrained braces (BRBs) are widely used as energy‐dissipation members in seismic areas, and BRBs with 10–20 m workpoint lengths have been applied in practice, particularly in tall buildings and spatial structures. This paper investigates the adverse effects of the core yield length on the compressive overstrength factor, local compressive and tensile strains, and fatigue demands. Sets of 2D shell and 3D solid models were analyzed using Abaqus, considering core yield lengths of up to 14 m and LY100, LY225, SN400B, SN490B, SA440B, and SA700 steel grades. Higher‐mode buckling and friction were shown to significantly amplify the compressive strain at the core ends and tensile strain at midspan, in part due to cyclic strain ratcheting, introducing the potential for core binding and premature necking. From these results, simple equations were proposed to calculate the compressive overstrength factor and to select the larger strong axis debonding gap and smaller design strain required for long BRBs.