Most of the existing techniques for detection of dopamine take the advantage of its ease of oxidation. The common problem is the presence of ascorbic acid, that coexists with dopamine in the extracellular fluids of human beings’ central nervous system, and is oxidized at nearly the same potential as dopamine. In this research an electrochemical biosensor based on poly(aniline boronic acid) nanocomposites filled with multi walled carbon nano tubes (CNTs) is being developed. This biosensor aims to eliminate the direct oxidation of dopamine, and simultaneously detect dopamine and ascorbic acid in a physiological pH environment. Using an in-situ electrochemical polymerization technique, a nanocomposites of poly(aniline boronic acid) were synthesized on the surface of a glassy carbon electrode. In this work CNTs have been modified using DNA, which enables dispersion of bundled CNTs in aqueous solution. Electrochemical polymerization of 3-aminophenylboronic acid monomer was conducted using a cyclic voltammetry (CV) technique using either a DNA@CNTs/glassy carbon electrode, a pristine CNTs/glassy carbon electrode, or a bare glassy carbon electrode as the working electrode, a platinum wire as the counter electrode, and an Ag/AgCl as the reference electrode. Poly(aniline boronic acid) was then electro-polymerized onto the surface of the electrode by sweeping the potential from -0.16 to 0.94 V (versus Ag/AgCl), in an electrolyte solution containing 3-aminophenylboronic acid monomer. The onset potential for polymerization of the poly(aniline boronic acid) backbone at an electrode modified with DNA@CNTs was shifted to lower values. Finally, the glassy carbon electrodes modified with poly (aniline boronic acid) nanocomposites were used as a working electrode in a three-electrode electrochemical sensor, to detect different concentrations of dopamine biomolecules in a phosphate buffered saline solution using a voltammetric method. Furthermore, the redox current for the polymerization of poly (aniline boronic acid) on this electrode was enhanced compared to the CNT modified and bare glass carbon electrodes.