Traditional interferometric fiber optic gyroscopes (IFOGs) are constrained by performance bottlenecks inherent in separate system architectures, which severely impede further enhancements in navigation system capabilities. The integration of IFOG technology with optical engine chips offers a compelling solution to these bottlenecks. This paper reviews the integrated optical engine chip technology used in IFOG systems. The paper begins with an overview of the basic working principles of IFOGs, based on the Sagnac effect, and investigates the development of multifunctional integrated optical engine chips using various materials, including silicon, indium phosphide, silicon dioxide, and silicon nitride. Subsequently, the paper presents a comprehensive analysis of the current state of hybrid integrated optical engine chips, showcasing recent advances in system integration and functional diversity. Finally, the main challenges encountered in current research and application are analyzed, and the future development path of integrated optical engine chip technology in the IFOG field is discussed.