Buckling of steel reinforcement usually causes a sudden loss of the load-carrying capacity and leads to the ultimate state of conventional reinforced concrete (RC) columns. However, it behaves differently in fiber-reinforced polymer (FRP)-confined RC columns due to the lateral confinement effect of FRP. This paper presents a theoretical study into the buckling behavior of longitudinal steel reinforcing bars embedded in FRP-confined concrete subjected to cyclic axial compression. An empirical monotonic compressive stress-strain model for laterally supported reinforcing bars considering the buckling effect, which was proposed in the authors’ previous study, was extended to a cyclic stress-strain model following the Menegotto-Pinto model accounting for the cyclic loops. The cyclic stress-strain models for laterally supported reinforcing bars as well as FRP-confined plain concrete were then implemented into the OpenSees platform to simulate the cyclic compressive behaviour FRP-confined RC columns and validated through comparisons with test results. The proposed cyclic stress-strain model for laterally supported reinforcing bars can serve as a fundamental law for the modelling of seismic behaviour of FRP-strengthened RC columns, especially for those with sparely- spaced transverse ties where buckling of reinforcing bars becomes a significant concern.