In this study, the effect of pure and modified hexagonal boron nitride (h-BN) nanosheet incorporation on the stability, viscosity, and electrochemical behavior of a waterborne emulsion acrylic coating was studied. The functionalization of h-BN nanoplatelets with polyacrylic acid (PAA) plasma polymerization was performed, and the successful surface modification was determined through water dispersion testing, Fourier transform infrared spectroscopy and thermogravimetric analysis, X-ray photoelectron spectroscopy, and also by transmission electronic microscopy. Later, the stability and viscosity properties of emulsion nanostructured acrylic coatings, which were previously prepared by an ultrasound-assisted mixing system, were analyzed using zeta potential and rheometry testing, respectively. The electrochemical behavior was analyzed by electrochemical impedance spectroscopy. The results prove an effective deposition of PAA films on the h-BN surfaces, which enhanced the stability and viscosity acrylic of nanostructured coatings due to the interactions between the h-BN nanoplatelets surface and emulsion acrylic paint and also with the thickener additives. On the other hand, the electrochemical analysis demonstrated a significant increase (two orders of magnitude) in corrosion resistance in the acrylic nanostructured coatings with 1 wt.% of unmodified and modified h-BN nanoplatelets concerning pure acrylic paint due to a barrier protection mechanism of corrosion inhibition. Therefore, the results demonstrate that the surface modification of h-BN by plasma polymerization (green technology) helped to solve the low dispersibility issue of BN nanosheet surfaces in a waterborne polymer matrix to obtained green nanostructured acrylic coatings with the right balance in in-can properties and corrosion inhibition of AISI 304 stainless steel.