Sensors form an integral part of our everyday lives in a wide range of disciplines ranging from detection of environmental toxins, quality control in food and water to healthcare and general safety. Nanomaterials such as carbon nanotubes (CNTs) owing to their small size, high electrical and thermal conductivity, high specific area and superior electronic properties are strong candidates for analyte detection and are thus being increasingly incorporated in sensor architecture. The electrically conducting polymers (CPs) are known to possess numerous features in terms of stability and ease of processing. Their high chemical sensitivity, room temperature operation and tunable charge transport properties has made them ideal for use as transducing elements in chemical sensors. Utilizing the property of surface modification of CNTs, CPs-CNT hybrid structures have been developed by electropolymerization. These hybrid structures exhibit the synergistic benefits of both the materials and allow rapid electron transfer for the fabrication of efficient sensors. This chapter focuses on the synthesis, characterization and applications of conducting polymer-CNTs hybrid nano bio/chemical sensors in various modes of sensor configurations towards sensing gases; volatile organic compounds (VOCs) and biomolecules whose detection and analysis plays a crucial role in environmental pollution control, medical diagnostics and food safety. © 2015 by Nova Science Publishers, Inc. All rights reserved.