Insect symbionts and their metabolites are complex and diverse and have potential medical values. Some culturable symbionts in insects can be used to accelerate wound healing and treat the irritable bowel syndrome. The culturable symbionts in insects can produce a variety of active compounds. Among them, organic acids, antimicrobial peptides, and alkaloids can inhibit the pathogens of humans; lipases, yeast killer toxin (KT), and reactive oxygen species can kill malaria parasites; peptides, polyketides, and esters can inhibit human tumors. However, due to the limitations from immature isolation and culture methods, insufficient clinical trials, and clinical adverse reactions caused by their secondary metabolites, the application of insect symbionts in the medical field is still in its infancy. This paper reviews the medical functions of insect symbionts and their metabolites and summarizes the status, problems, and solutions in the application of insect symbionts and their metabolites in the medical field, aiming to give insights into the study and application of functional symbionts.