Neoadjuvant immunotherapy for rectal cancer has become a research hotspot in recent years, and early clinical trials exhibit encouraging outcomes. Generally speaking, immune checkpoint inhibitors (ICIs) have shown higher safety and cause no increase in surgery-related complications, but a small proportion of patients may experience severe immune-related adverse events (irAEs) that can impact subsequent treatments or threaten life. Currently, clinical research on neoadjuvant immunotherapy is in its early stages, with small sample sizes and relatively young, generally healthy patients being included. The safety for special populations, such as the elderly or those with autoimmune diseases, remains to be confirmed. Research on the mechanisms, prediction, diagnosis, and management remains insufficient. ICI treatment typically combines with chemoradiotherapy, complicating irAE diagnosis and management. Therefore, guidelines for managing adverse reactions to neoadjuvant immunotherapy should be established. Neoadjuvant immunotherapy regimens include multifarious methods such as concurrent immunotherapy with chemoradiotherapy, sequential chemoradiotherapy followed by immunotherapy, and total neoadjuvant therapy (TNT) combined with immunotherapy. The number of immunotherapy sessions also varies. Larger-scale clinical studies are required to develop personalized treatment plans that maximize efficacy and minimize adverse reactions.