Biosensors are the subject of an immensely growing field of research owing to their broad range of applications in medicines, pharmacy, environmental monitoring, food and process control, defense and security, and principally in diagnostics. Diverse materials have been investigated for the advancement of biosensors in terms of their miniaturization, sophistication, cost, biosensing features, ie, detection limit, sensitivity, stability, selectivity, etc. Polyaniline (PANI) is one of the most interesting conductive polymers for biosensor design in view of its excellent electrochemical properties (polyelectrocatalytic characteristics, reversible redox behavior, and electrochemical tunability), straightforward processability, long-term environmental stability, and functionality-rich chemical structure. In this review, an attempt is made to compile almost all the existent literature on PANI-based biosensors in terms of enzymatic biosensors (for H 2 O 2 , glucose, cholesterol, phenol/polyphenol/catecholamine detection), genosensors (DNA sensing), and immunosensors from 2006 to 2015. Furthermore, reports available on the biosensing of urea, uric acid, creatinine, pesticides, amino acids, and other clinically significant analytes are also assembled to provide a comprehensive overview on PANI-based biosensors.