MicroRNAs (miRNAs) are small non-coding RNAs (approximately 22–30 nucleotides long) that work as regulatory molecules inhibiting gene expression after binding to their target mRNAs and silencing them, affecting the expression of the proteins. miRNAs regulate several functions in a cell, including cell development, proliferation, and apoptosis. In cancer, there is an alteration in miRNA biogenesis that affects their expression, and these molecules play two different roles in promoting or suppressing tumor growth. On the other hand, tumors use miRNAs to evade the immune response and continue proliferating. Tumor-secreted miRNAs modulate different types of cells, including macrophages, NK cells, dendritic cells, and T cells. This chapter summarizes the current knowledge of the implications of tumor miRNAs in the modulation of the immune response in cancer and their association with immune escape. We also discuss the role of immune cell-derived miRNAs and the use of these molecules as therapeutic tools in cancer.