CNTs are hollow cylindrical tubes made up of carbon, having a very high aspect ratio (length/diameter). They have one, two or several concentric graphite layers, capped by fullerenic hemispheres. The single-walled CNTs (SWCNTs) and multi-walled CNTs (MWCNTs) are the most commonly used CNTs (Figure 1), although double-walled CNTs, bamboo CNTs and herringbone have also been developed. The developments in the technology during the last two decades have considerably improved the synthesis and functionalization of CNTs, thereby, resulting in the cost-effective production of CNTs in bulk quantities, and their extensive use for bioanalytical applications. The chemical vapor deposition is the most widely used technique for CNTs synthesis, whereas, arc discharge and laser ablation have also been employed. Various strategies have been devised for the functionalization of CNTs with different chemical groups; conjugation of CNTs to biomolecules; and the preparation of CNT-based electrodes. CNTs have several unique features, i.e. high mechanical strength, high thermal conductivity and chemical stability, which make them prospective nanomaterial for ECS. The main characteristic of CNTECS is their rapid response with low limit of detection, which is mainly due to their high surface area, low overvoltage and rapid electrode kinetics [2].CNT-ECS have been developed for the detection of glucose, neurotransmitters/neurochemicals, proteins, cells, DNA, microorganisms, pharmaceutical substances and other biomolecules. The direct electron transfer between the enzyme and the CNT-based electrode has further led to the development of mediatorless CNTECS with highly precise analyte detection, as they have negligible interferences from electroactive physiological substances and drug metabolites. The chemically-functionalized, vertically-aligned CNTs have also been developed by several researchers and shown to be more sensitive. But, these are highly expensive for the end-users’ applications. A wide range of CNT-based nanocomposites and ionic gels have also been developed, to improve the analytical performance of CNT-ECS. CNTs are very promising candidates for the development of next-generation DDS. CNT-DDS enable the delivery of drugs and biomolecules with a very high efficiency due to their large surface area; unique structural, electrical and optical properties; well-defined physico-chemical properties; and no toxicity (using functionalized CNTs). Several conjugation strategies have been developed to covalently/non-covalently bind the drugs/biomolecules to CNTs. CNT-DDS have been extensively employed for the delivery of anticancer, anti-inflammatory and other drugs, in addition to the delivery of biomolecules, i.e. DNA, RNA and proteins [3]. Various formats of CNT-DDS, such as CNT bottles have also been developed [4]. However, despite the significant developments, there are still numerous challenges that need to be tackled before CNT-ECS and CNT-DDS become commercially-viable. The synthesis of ultrapure CNTs without any metallic impurities at a low cost is the main challenge. The pristine CNTs, being intrinsically hydrophobic, cannot disperse uniformly in most solvents and biological media. Therefore, the development of biocompatible CNTs by strategies involving surface modification, surface functionalization or bioconjugation, is critical in order to avoid the toxicity of CNTs. Moreover, the current market price of CNTs is too high and needs to be significantly reduced for realistic commercial applications.