<p>This review assesses hydrogen and ammonia as vital carbon-free fuels for reaching net-zero emissions. It emphasizes hydrogen’s high energy density and versatility for hard-to-electrify sectors, while noting ammonia’s dual role as an efficient hydrogen carrier and a direct fuel that simplifies storage and transportation. Despite these benefits, significant barriers persist across technology, infrastructure, and markets—such as high costs, limited green hydrogen capacity, and inadequate transport and storage systems. Accelerating progress therefore depends on technological advances (like improved electrolysis efficiency, new catalysts, and membranes), scalable manufacturing to cut costs, and strong policy support. Reliable, safe storage and resilient transport networks—along with integrated planning to manage renewable intermittency through long-duration storage, demand response, and hybrid supply chains—are crucial. Finally, adopting a value-chain approach that links production, conversion, logistics, and end-use, supported by harmonized standards, regulatory frameworks, market incentives, digital tools, and cross-border cooperation, will be essential for commercialization.</p>