Synthetic messenger RNA (mRNA)-based therapeutics have emerged as promising candidates for the prevention and treatment of a wide range of diseases and disorders. mRNA possesses notable advantages, including exceptional safety, the capacity to replace various functional proteins produced by the human body, and the flexibility and industrial scalability of mRNA design and synthesis. In this review, we aim to summarize the latest advancements in mRNA nanotherapy and explore recent breakthroughs in the development of mRNA delivery systems, such as lipid-, polymer-, and polymer-lipid hybrid-based platforms. Notably, we highlight recent innovations in mRNA-based nanotherapy for cancer treatment, encompassing protein replacement, vaccines, cell-based therapies, and gene editing. Furthermore, we present our insights on the future prospects and remaining challenges in harnessing the potential of mRNA-based nanotherapy in the battle against cancer.