<p>Signal amplification strategies are vital to the advancement of electrochemical biosensors and enable the sensitive, selective, and reliable detection of low-abundance analytes. This review provides a comprehensive overview of recent nanomaterial-based strategies to signal amplification in electrochemical biosensors, material innovations, and their applications. Key categories discussed include metallic nanomaterials, carbon-based nanomaterials, and quantum dots, which enhance biosensor performance through unique properties such as high surface area, superior conductivity, and catalytic activity. Furthermore, emerging strategies involving advanced materials, such as metal-organic frameworks, polymer-based nanomaterials, and metal-free semiconductors, are explored for their ability to not only amplify signals but also enhance stability, biocompatibility, and ease of functionalization. The integration of these materials into biosensor platforms has enabled innovative solutions in medical diagnostics, environmental monitoring, and food safety. This review categorizes the key nanomaterials, details the underlying mechanisms of signal amplification (e.g., enhanced surface area, conductivity, and catalysis), and explores emerging strategies and applications in diagnostics. This work highlights the significant progress achieved and charts a path toward future innovations, including scalable, stable, and multifunctional hybrid systems.</p>