In this work, Langmuir-Blodgett (LB) technique was proposed to assemble the homogeneous and controlled films of carboxylic multiwalled carbon nanotubes-Nafion (c-MWCNTs-Nafion). Microstructure and electrochemical performance of LB films of c-MWCNTs-Nafion were characterized by AFM, SEM and electrochemical experiments. Moreover, the LB film of c-MWCNTs-Nafion was transferred to the surface of glassy carbon (GC) electrode to fabricate the electrochemical voltametric and amperometric sensor for codeine. The fabricated sensor showed enhanced electrocatalytic behavior for the oxidation of codeine. The amperometric currents for codeine are proportional to its concentration in a range from 1.0 x 10(-7) to 1.0 x 10(-5) mol L-1 with a detection limit of 3.0 x 10(-8) mol L-1. And the proposed method exhibited good repeatability, stability, selectivity and accuracy. (C) 2019 The Electrochemical Society.