While the impacts of cigarette smoking on human health are widely known, a less recognized impact of tobacco product use and disposal is environmental pollution. This review discusses the current literature related to cigarette and e-cigarette contamination in the context of environmental sources and impacts, with a focus on the documented influences on biota, ranging from bacteria to mammals. Cigarette butts and electronic cigarette components can leach contaminants into soil, water, and air. Cellulose acetate cigarette filters comprising the butts are minimally degradable and are a source of bulk plastic and microplastic pollution, especially in aquatic ecosystems where they tend to accumulate. Cigarette combustion and aerosol production during e-cigarette use result in air contamination from sidestream, exhaled, and thirdhand pathways. The chemical byproducts of tobacco product use contaminate wastewater effluents, landfill leachates, and urban storm drains. The widespread detection of nicotine and cotinine in the environment illustrates the potential for large-scale environmental impacts of tobacco product waste. Studies show that cigarette butt leachate and nicotine are toxic to microbes, plants, benthic organisms, bivalves, zooplankton, fish, and mammals; however, there remain critical knowledge gaps related to the environmental impacts of tobacco product waste on environmental health and ecosystem functioning.