The tumor microenvironment is a complex structure surrounding cancer cells with various cell types, involving stromal and immune cells, including epithelial cells, fibroblasts, and adipocytes. Meanwhile, a solid relation between obesity and the risks of cancer has been indicated by accumulated epidemiological studies. Therefore, it is essential to elucidate the interconnection between adipocytes and other cells, including cancer cells on its tumor microenvironment. White adipose tissue (WAT) and brown adipose tissue (BAT), the two significant kind of lipid depots, have different molecular mechanisms for the promotion of cancer development. Besides supplying the unusually high energy requirement, WAT also stimulates development and metastasis of cancer cells through a variety of lipid metabolites and adipokines, while BAT is particularly associated with cancer cachexia. In this chapter, we emphasize the underlying interaction between WAT/BAT and other cell types in the tumor microenvironment, as well as tumor cells. We also mention the impact of obesity on cancers and furthermore highlight molecular targets that have been utilized for therapeutic strategies.