In this study, we developed a highly sensitive automatic counting method for gold nanomaterials at the single particle level, which can serve as a general sensing platform based on counting of gold nanomaterials. This method substantially improved the sensitivity and accuracy for AuNP counting by adopting the color image processing based on the distinctive localized plasmonic light-scattering of gold nanomaterials. The 60-nm AuNPs, with concentrations down to 4 fM, can be detected with our method. As a universal counting approach for gold nanomaterials, such as gold nanospheres, nanorods, and aggregates from particles under detectable size, this quantification method should be versatile to a breadth of applications.