A novel fabrication approach for electrochemical sensing of nicotinamide adenine dinucleotide (NADH) using neutral red (NR) functinalized carbon nanotube/plasma-polymerized film composite electrode is reported. The configuration of sensing electrode was NR-functionalized CNTs sandwiched between two acetonitrile PPFs on sputtered gold thin film. The NR as an electron transfer mediator shuttles the electron from the CNT to gold electrode. Due to the synergistic effect between NR and CNT, the resulting electrode showed the lower detection potential and the larger sensitivity (current) than that of NR or CNT alone. The sensor revealed a sensitivity of 29µA mM^-1cm^-2 at +0.15V vs. Ag/AgCl, linear dynamic range of 0.08-4.2mM, a detection limit of 18µM at S/N=3, and a response time of 7s.