Three-dimensional (3D) woven and knitted spacer fabrics have emerged as significant advancements in the field of technical textiles, driven by notable progress made by the textile industry. These unique fabrics possess desirable characteristics that render them suitable for various technical applications. As we look towards the future, spacer fabrics are expected to find innovative applications in various functional products. However, despite the growing interest in their use in the technical textile sector, comprehensive reviews exploring their potential are lacking. Therefore, this review aims to fill this gap in the existing literature by examining the potential of 3D woven and knitted spacer fabrics in technical textiles. It provides a comprehensive exploration of their fabrication techniques, properties, key parameters, and potential applications in technical textiles. This review highlights that woven spacer fabrics exhibit high integrity and stability, making them suitable for composite reinforcement. On the other hand, knitted spacer fabrics offer a higher air-trapping capacity and a double-faced nature, leading to their extensive use in cushions, medical textiles, and protective technical textiles. Additionally, this review provides valuable insights for researchers and manufacturers interested in harnessing the potential of spacer fabrics for various functional products in the field of technical textiles.