This paper proposed ambient light (ambilight) as a new type of signal sources for positioning. The possibility and methods of ambilight positioning were presented in this paper. It has been shown that two kinds of observables of ambient light can be used for positioning through different principles. Ambilight intensity spectrum measurements have highly location dependency, and they can be used for positioning with the traditional fingerprinting approach. Total ambilight irradiance intensity is used to detect the proximity of a lighting source, and a location solution can be further resolved with the support of knowledge of lighting infrastructure. Ambilight positioning can work in areas where other traditional techniques are not able to function. An ambilight sensor is cost-efficient and miniature in size, and it can be easily integrated with other sensors to form a hybrid positioning system. This paper was concluded with discussions on the possibility, applicability, challenges and outlook of the new ambient light positioning techniques.