An image sensor package and a method for fabricating the same are provided. The image sensor package includes a first substrate comprising a via hole therein, a driving circuit and a first conductive pad thereon. A second substrate comprising a photosensitive device and a second conductive pad thereon is bonded to the first substrate, so that the driving circuit, formed on the first substrate, can electrically connect to and further control the photosensitive device, formed on the second substrate. A solder ball is formed on a backside of the first substrate and electrically connects to the via hole for transmitting a signal from the driving circuit. Because the photosensitive device and the driving circuit are fabricated individually on the different substrates, fabrication and design thereof is more flexible. Moreover, the image sensor package is relatively less thick, thus, the dimensions thereof are reduced.