Plant diseases caused by pathogens and pests lead to crop losses, posing a threat to global food security. The secretory pathway is an integral component of plant defense. The exocyst complex regulates the final step of the secretory pathway and is thus essential for secretory defense. In the last decades, several subunits of the exocyst complex have been reported to be involved in plant defense, especially Exo70s. This comprehensive review focuses on the functions of the exocyst Exo70s in plant immunity, particularly in recognizing pathogen and pest signatures. We discussed Exo70's interactions with immune receptors and other immune-related proteins, its symbiotic relationships with microbes, and its role in non-host resistance. Finally, we discussed the future engineering breeding of crops with resistance to pathogens and pests based on our current understanding of Exo70s.