f-MWCNTs/BB modified electrode which contains functionalized multi-walled carbon nanotubes (f-MWCNTs) and Brilliant blue FCF (BB) has been synthesized on glassy carbon electrode (GCE) and indium tin oxide (ITO). The presence of f-MWCNTs enhances the surface coverage (Γ) and stability in the pH range between 1.0 to 13. Electrochemical impedance spectra (EIS) was applied to monitor the whole process of the electrode modification. UV–visible absorption spectra results confirmed that the f-MWCNTs/BB film was successfully eletropolymerization on the electrode surface. We have studied the surface morphology of the modified electrode using scanning electron microscopy (SEM) and atomic force microscopy (AFM), which revealed that BB is coated on f-MWCNTs. The cyclic voltammetrys (CVs) has been used for the measurement of electroanalytical properties of analytes by means of modified electrodes. The sensitivity values of f-MWCNTs/BB modified glassy carbon electrode are higher than the values which are obtained for only BB film and f-MWCNTs modified electrode. Finally, the amperometry method has been used for the detection of hydrogen peroxide at f-MWCNTs/BB modified electrode under stirred condition. The f-MWCNTs/BB modified electrode also exhibits a promising enhanced photoelectrocatalytic activity for hydrogen peroxide under illumination.