<p>The rapid proliferation of the Internet of Things (IoT) has unlocked unprecedented opportunities across consumer, industrial, medical, and environmental sectors. However, this growth has also led to a significant increase in electronic waste (e-waste), raising concerns about resource depletion and long-term ecological impact. In response, biodegradable and transient antennas (BTAs) have emerged as promising solutions for building sustainable, eco-friendly wireless systems. These antennas are engineered to degrade naturally or dissolve after fulfilling their operational purpose, thereby minimizing their environmental footprint without compromising functional performance. This paper presents a comprehensive review of the design, materials, fabrication techniques, and performance considerations associated with BTAs for IoT applications. The discussion highlights recent advances in biodegradable conductors and substrates, examines critical challenges such as conductivity, mechanical stability, and system-level integration, and proposes innovative strategies to overcome these limitations. In addition, the review explores a range of application domains, including disposable electronics, implantable medical devices, and environmental monitoring platforms, where degradable antenna systems offer unique advantages. Finally, the potential convergence of artificial intelligence (AI) driven IoT ecosystems with green antenna technologies is discussed, outlining future directions for research and development. This work is intended to serve as a foundational resource for engineers, materials scientists, and researchers committed to advancing sustainable electronics and green communication infrastructures.</p>