MCP-1, also known as CCL2, is a chemokine that plays a central role in inflammation and immune responses. It is primarily produced by various cell types, including monocytes, macrophages, endothelial cells, fibroblasts, and epithelial cells. MCP-1 is crucial for the recruitment, activation, and migration of leukocytes, particularly monocytes and macrophages, to the site of inflammation. It is involved in the pathogenesis of numerous diseases, including COVID-19, cancers, neuroinflammatory diseases, rheumatoid arthritis, and cardiovascular diseases, by promoting the migration and infiltration of inflammatory cells. Additionally, MCP-1 contributes to insulin resistance, diabetes, and its complications, such as diabetic nephropathy and retinopathy, by increasing the level of circulating MCP-1 in type 1 and type 2 diabetes. Furthermore, it plays a role in cancer by recruiting macrophages to the tumor microenvironment, promoting angiogenesis, and inducing cell invasion and metastasis. Overall, MCP-1 is a key chemoattractant with functions that extend beyond immunity, influencing a wide range of pathological processes.