The increasing demand for small and effective antennas in contemporary wireless communication, aerospace, and medicinal systems has prompted research into materials that can facilitate antenna shrinking without compromising performance. Although they are frequently utilized, conventional substrates like PTFE and FR4 provide little opportunity for additional size reduction. Because of their high dielectric constants, lead-based perovskites have long been thought to be successful; nevertheless, safer alternatives are required due to their toxicity and environmental issues. Lead-free perovskite materials, including BaTiO3, BCZT, Na0.5Bi0.5TiO3, Aurivillius phases, and spinel-perovskite composites, are the main topic of this chapter. We go into great length about their dielectric characteristics, production methods, and suitability for patch antenna substrates. Their stability, permittivity, and dielectric loss all of which have a direct impact on antenna efficiency and miniaturization are given particular consideration. All things considered, lead-free perovskites offer a high-performing, sustainable family of materials with great potential for use in next-generation antenna applications.