<p>A growing desire for the availability of clean energy in the railway environment has led to advancements in energy harvesting technologies. In particular, piezoelectric energy harvesters (PEHs) have been shown to have potential benefits for the railway industry. Thus, this paper provides a review of PEH solutions for railway energy harvesting, focusing on their design, optimization, and implementation. It examines various energy sources, including vibration, mechanical stress, friction, sound, and wind energy, while also discussing the structural designs and materials employed to improve their performance. The review highlights the potential applications of PEHs in powering self-sustaining wireless sensors, monitoring systems, and trackside electronics. Despite notable advancements, challenges persist, particularly in energy conversion efficiency, structural durability, data transmission, and the integration of interface circuits. The paper further explores potential future research directions, underscoring the need for more efficient energy harvesting systems, multi-mechanism coupling, and robust solutions for the harsh environmental conditions under which railways operate. If future research can address these challenges, PEHs hold promise for powering smart and sustainable railway infrastructure.</p>