Cold-formed steel (CFS) members are susceptible to geometric imperfections due to the high length-to-thickness ratio of the flat partitions, in other words, high slenderness. Geometric imperfections should be considered in the design and analysis of the CFS members since they significantly affect the structural behavior and performance of the investigated members. Despite its importance and numerous studies performed on this topic, no obvious guideline presents all the necessary information on the geometric imperfections of CFS members. This review study aims to close this gap resulting from the lack of information by providing a comprehensive review of the geometric imperfections of CFS members from different aspects, such as measurement techniques, characterization, characteristics, and modeling approaches. Additionally, guidelines presented in code provisions for geometric imperfection modeling are reviewed.