A novel nanocomposite of Zn–Al layered double hydroxide (LDH) and poly acrylic acid-functionalized multi-walled carbon nanotubes was assembled successfully through interfacial electrostatic interaction between the positively-charged layers of LDH nanocrystallites and the negatively-charged functional groups on the surface of functionalized carbon nanotubes. The resulting glassy carbon electrode modified by as-assembled nanocomposite exhibited excellent electrochemical activity toward the oxidation of catechol. The oxidation peak potential difference of catechol and hydroquinone was achieved at modified electrode, which could effectively distinguish catechol from hydroquinone. The present work provided a new method for electrochemical determination of dihydroxybenzene isomers with high sensitivity.