Insulin (INS) and the insulin signaling pathway (IIS) have attracted considerable research interest due to their unique role in hypoglycemia. Recent progress has revealed that IIS not only regulates a variety of physiological activity in mammals but also has a similar role in insects. IIS plays a regulatory role in insect growth, development, reproduction, feeding, and immunity. This article introduces the types of IIS in insects, describes the structure and function of IIS related genes, and the insulin-like protein (ILP), insulin receptor (InR) and forkhead transcription factor O family (FoxO). The role of IIS in different aspects of insect life, such as chemoreception, life span, immunity, and phenotypic plasticity, are described. IIS regulates the life activities of insects by regulating the expression of related genes and influencing the activity of related functional proteins, thereby allowing insects to adapt to environmental changes. Due to the highly conserved nature of IIS among different species, the study of IIS not only provides a theoretical basis for the utilization and management of insects in agricultural production, but also provides information that may contribute to the regulation of human development, resistance to aging and disease treatment.