Electrogenerated chemiluminescence of organic nanoparticles has been observed and described. Highly fluorescent organic nanoparticles may emit light upon applying a certain potential on their aqueous or nano aqueous solutions, even in the their solid state films. Such phenomenon will open a vast realm of tailoring many types of fluorophores and organic nanoparticles in order to get unique physical, mechanical, biological, and optical properties in material sciences area.