Macrophages are a type of white blood cells that can exist in two different functional states, known as M1 and M2. M1 macrophages secrete pro-inflammatory cytokines that can promote tumor growth and metastasis, whereas M2 macrophages secrete anti-inflammatory cytokines that can inhibit tumor progression. This phenomenon, referred to as macrophage polarization, has been implicated in the development and progression of cancer. Furthermore, macrophage polarization is currently being investigated in the context of COVID-19 severity. It is believed that M1 macrophages may contribute to the excessive inflammation observed in severe COVID-19 cases, while M2 macrophages may confer protection against the disease. Hence, comprehending the role of macrophage polarization in both cancer and COVID-19 has the potential to enhance treatment strategies for both conditions.