A semiconductor optical sensor (1) is provided with: a substrate (2) integrating a plurality of photodetector active areas (4); and a CMOS layer stack (6) arranged on the substrate (2) and including a number of dielectric (6a) and conductive (6b) layers. UV conversion regions (10) are arranged above a number of first photodetector active areas (4) to convert UV light radiation into visible light radiation towards the first photodetector active areas (4), so that the first photodetector active areas (4) are designed to detect UV light radiation. In particular, the first photodetector active areas (4) are alternated to a number of second photodetector active areas (4), designed to detect visible light radiation, in an array (15) of photodetection units (16) of the optical sensor (1), defining a single image detection area (15′), sensitive to both UV and visible light radiation with a same spatial resolution.