Hydrogen has been proposed as a clean energy source to replace fossil fuels. The hydrogen economy encompasses the production, storage, transport, and use of hydrogen. Among the various potential hydrogen carriers, ammonia is considered an efficient and economical option due to its established infrastructure for production, storage, and transport. In this ammonia value chain, ammonia decomposition enables the efficient and sustainable production of carbon-free hydrogen. Recently, Co has gained attention as an active metal for thermal ammonia decomposition due to its excellent catalytic performance and cost-effectiveness. This review presents current developments in supported and unsupported Co-based catalysts for ammonia decomposition. Key strategies to enhance the hydrogen formation rate include optimizing the Co precursor and synthesis methods, incorporating a second active metal and promoters, tuning the physical properties of the catalyst, and doping heteroatoms into the support. Practical considerations for the preparation of Co-based catalysts are also outlined. This review provides valuable insights into the development of advanced Co-based catalysts for ammonia decomposition, with the aim of guiding future research toward highly efficient, cost-effective, and scalable hydrogen production solutions.