A complementary metal-oxide semiconductor (CMOS) image sensor and a method for fabricating the same are disclosed. The CMOS image sensor a plurality of photosensitive devices formed on a semiconductor substrate, an interlayer dielectric formed on the photosensitive devices, and a plurality of color filter layers facing into each interlayer dielectric and filtering light for each wavelength, a planarization layer formed on each of the color filter layers, and a micro-lens layer formed on the planarization layer and having a refractive index distribution, in which light is focused to the photosensitive device facing thereto, based on an ion injection profile.