Pollutants made by industries and chemical laboratories have a harmful effect on human health and the environment. Concerns raised by this problem have led to the development of more versatile and sustainable protocols based on green chemistry principles. One of these innovative approaches is conducting the reactions under visible-light sources in the absence of photocatalysts. This benign, simple, and inexpensive method, which was inspired by nature, may be an appropriate alternative for some classic methods, turning the harsh reaction conditions into milder ones. In this review, we overview the catalyst-free organic transformations under visible light. The proposed mechanisms were discussed, including formation of electron donor-acceptor (EDA) complex, single electron transfer (SET).