This Review explores how tumor-associated regulatory cells (Tregs) affect cancer immunotherapy. It shows how Tregs play a role in keeping the immune system in check, how cancers grow, and how well immunotherapy work. Tregs use many ways to suppress the immune system, and these ways are affected by the tumor microenvironment (TME). New approaches to cancer therapy are showing promise, such as targeting Treg checkpoint receptors precisely and using Fc-engineered antibodies. It is important to tailor treatments to each patient's TME in order to provide personalized care. Understanding Treg biology is essential for creating effective cancer treatments and improving the long-term outcomes of immunotherapy.