**Abstract**

Polymer nanocomposites (PNCs) play a significant role in modern day life and are widely studied for extensive properties which make them appealing to numerous applications. They are synthesized with scalable processing procedures with several nanoscale variations of fillers and forms leading to specific sensing applications. In this chapter, PNC-based electrochemical sensors and biosensors like DNA biosensors and immunosensors are discussed. These sensors related PNC applications uses nanofillers of various combinations like conductive polymers with graphene (Grp), carbon nanotubes (CNTs), and metal nanoparticles, which endow high electrical conductivity, effective surface area, and fast electron transfer rate. Currently, wearable devices based on electrochemical Sensors and biosensors have been of great interest in the detection of both physiological and environmental analytes.

**Keywords:** polymer nanocomposites, electrochemical sensors, biosensors, DNA sensors, immunosensors
