Conductive polyaniline (PANI)-coated polyvinylidene fluoride (PVDF) composite nanofiltration (NF) membranes were synthesized by an in situ chemical oxidative interfacial polymerization (solution and diffusion cell polymerization) to produce pressure filtration membranes with tunable separation selectivity through applying an external electrical potential. The diffusion cell polymerization technique was found to be superior with ability to coat a greater thin layer PANI film (120% mass increase) than solution polymerization (13% mass increase) after 48 h of reaction time. Furthermore, the conductivity of the PANI membrane synthesized by diffusion cell polymerization was far higher than that of the solution polymerization membrane, which was up to 6.711 S/cm compared to 7.61 × 10^–2 S/cm, respectively, showing that a continuous film with good electrical connectivity has been formed. Meanwhile, a modified dynamic contact angle test showed that the membranes were electrically tunable with about 30–40% decrement on the contact angle values after an external electrical potential was applied. Moreover, the membranes with a complete surface PANI coverage (around 30–80 mass percentages) confirmed to have their permeability for neutral species (polyethylene glycols) electrically tuned under cross-flow conditions. Overall, this work demonstrated that the diffusion cell polymerization method produced membranes that have the potential to be applied as electrically tunable NF membranes.