The velocity profiles of unsteady flow in simple channel section are different as compared to steady flow condition. The cross-sectional area of a flooded river usually comprises of a deep main channel and adjoining shallow floodplains called “compound section.” Unsteady flow often occurs in a compound channel making the flow process even more complicated due to the large variations in three-dimensional velocities. The velocity profile changes highly in a compound channel as compared to simple channel cases. Because of the difficulties in measurement of flow variables of open-channel flow during unsteady flow, studies conducted on open-channel flow in such conditions are very rarely found. An attempt has been now made to investigate the behavior of velocity profiles of a channel under unsteady flow conditions. Extensive literature study on unsteady flow in both the simple and compound cross-sectional channels has been carried out. A comparative study of velocity profiles is done. In unsteady flow, under compound channel flow case, the velocity profiles are found to be much dissimilar in rising limb cases in contrast to the falling limb cases. This is because the effect of the lateral momentum transfer (LMT) in a compound section is profound in the unsteady flow in contrast to steady flow cases. The recommendation to improve the existing equation of steady flow to be applicable for unsteady flow can be inferred from the analysis.