This chapter explores the development, properties, and applications of polymer/rubber-based nanoblends, a class of materials that combines the elasticity and flexibility of rubber with the strength and durability of polymers, enhanced further by nanoscale fillers. The integration of nanofillers, such as carbon nanotubes, silica, and graphene, offers significant improvements in mechanical strength, thermal stability, abrasion resistance, and chemical resilience, making these materials highly adaptable for demanding applications in industries including automotive, aerospace, healthcare, and electronics. Key challenges in compatibility between polymers and rubber phases are addressed through the use of compatibilizers and advanced blending techniques to achieve optimal interfacial bonding and stability. Furthermore, the chapter discusses recent advancements toward sustainability, highlighting the potential of bio-based and recyclable polymers in nanoblends as industries increasingly prioritize eco-friendly solutions. By analyzing the synthesis, customization, and application potential of polymer/rubber-based nanoblends, this chapter provides a comprehensive overview of their current and future role as versatile, high-performance materials capable of meeting both technical and environmental demands.