Recently, the corrosion of metals is an important academic and industrial concern which has received significant attention. Poly(o-phenylenediamine) (PoPDA) and poly (3-aminobenzoic acid) based nanocomposites with un-functionalized multi-walled carbon nanotubes (MWCNTs) and functionalized multi-walled carbon nanotubes (FMWCNTs) were prepared through emulsion polymerization using sodium dodecyl sulfate (SDS) as an emulsifier and ammonium persulfate (APS) as an oxidant. Fourier transform infrared (FT-IR) spectra confirmed the construction of the nanocomposites. The morphology of the synthesized nanocomposites was characterized using scanning electron microscopy (SEM). X-ray diffraction (XRD) patterns of the nanocomposites indicated a more crystalline nature than that of bare PoPDA and P3ABA. The thermal stability of the nanocomposites was improved relative to bare PoPDA and P3ABA. The corrosion protection performance of the coatings containing PoPDA@MWCNTs, PoPDA@FMWCNTs, PoPDA, P3ABA and P3ABA@MWCNTs on steel and copper was evaluated using potentiodynamic polarization, electrochemical impedance spectroscopic (EIS) and open circuit potential (OCP) measurements in 3.5% NaCl solution. The obtained results of the potentiodynamic polarization, EIS and OCP showed that the PoPDA@MWCNTs and P3ABA@MWCNTs nanocomposites coated steel and copper had excellent corrosion inhibition behavior in saline solution.