AbstractThe tumour microenvironment (TME) is a complex system composed of cancer cells, stromal cells and immune cells. Regulatory T cells (Tregs) in the TME impede immune surveillance of tumours and suppress antitumor immune responses. Transcription factor forkhead box protein 3 (FOXP3) is the main marker of Tregs, which dominates the function of Tregs. FOXP3 was originally thought to be a Tregs‐specific expression molecule, and recent studies have found that FOXP3 is expressed in a variety of tumours with inconsistent functional roles. This review summarizes the recent progress of infiltrating Treg‐FOXP3 and tumour‐FOXP3 in TME, discusses the communication mechanism between FOXP3+ cells and effector T cells in TME, the relationship between FOXP3 and clinical prognosis, and the potential of FOXP3‐targeted therapy.