miRNAs are small noncoding RNAs that regulate gene expression and play crucial roles in the activation and inhibition of various cellular processes like proliferation, cell division, and apoptosis. miRNAs have emerged as a promising therapeutic tool for targeting oncogenes and tumor-suppressive pathways. This chapter examines the therapeutic approaches where miRNAs are being used in inhibition strategies in various kinds of cancers alongside viral and nonviral delivery systems. There are several preclinical and clinical trials exploring the use of miRNA mimics and inhibitors to target oncogenic miRNAs. Both miRNA mimics and inhibitors struggle to reach the cancer site because of their stability, off-target effects, and toxicity. We discussed more specific and stable innovative delivery systems, such as miRNA-loaded nanoparticles and exosomes. Future research is more likely to focus on minimizing off-target effects, toxicity, increased target specificity, and expanding clinical applications of tumor suppressor miRNA therapies.