Sustainability is a key issue for the next-generation optoelectronic semiconductor devices. Currently, devices based on lead halide perovskite semiconductors are revolutionizing the optoelectronics field beyond photovoltaic. Despite breakthroughs in a wide range of applications, including solar cells, light-emitting diodes, lasers, sensors, transistors, X-ray detection, sustainability issues have emerged as a bottleneck challenge for further breakthroughs at the industrial level. To overcome this challenge, the development of lead-free perovskite semiconductors is a top priority of the next-generation semiconductor devices. Lead-free perovskite thin-film transistors (TFTs) are one such example. Currently, progress in this technology is on-going and holds great promise for achieving high performance in displays and other invisible electronic applications. Therefore, this chapter aims to introduce the main discussions and key aspects of lead-free perovskite transistors. These discussions include, but are not limited to, the basic principles of TFTs and their manufacturing techniques, key performance parameters, key components, operating principles, transition requirements for lead-free perovskite transistors, understanding charge transport, high-mobility lead-free perovskites transistors, key dimensions, and primary device architecture layouts, as well as the future development directions of these transistors.