Tumor-associated macrophages (TAMs) are the most abundant infiltrating immune cells in the tumor microenvironment (TME) and play an important role in tumor progression. Clinically, the increase of TAMs infiltration is linked to poor prognosis of patients with various cancer types. Multiple studies have demonstrated that reducing or reprogramming TAMs can inhibit the occurrence or development of tumors. Therefore, TAMs have been identified as novel targets for the treatment of cancer therapy. In this review, the origin, polarization, roles, and targeting of TAMs in malignancies, are discussed.