Across the globe, the livelihood of millions of people relies on the recovery and sale of valuable materials previously discarded as waste. In developed countries, this is mainly incorporated into the official recycling and resources recovery sector, while in developing countries the informal waste picking activities often make a major contribution. Waste picking provides important opportunities to people who have few or no marketable skills and education and no alternative sources of income to survive. However, waste pickers’ living conditions remain deplorable, and their working conditions continue to be dangerous due to hazardous waste. Given the social, economic, and environmental benefits waste pickers bring, and particularly their contribution to circular economy goals in developing nations, the role of waste pickers has mostly been undervalued on the development agenda. This paper examines the literature on waste pickers around the world, their working and living conditions, and explores the issue of formalisation. A total of 45 papers published from 1994 to 2022 were reviewed, covering case studies on waste pickers from 27 different countries. We analyse the content of these papers based on a list of key themes: poverty, health, stigma, environmental factors, informality, and formalisation. We find that the informal status of waste pickers, and the question of them being formalised into a Municipal Solid Waste Management sector is discussed extensively in the literature, and we delve deeper into this theme. Formalisation can potentially bring considerable improvement to the lives of waste pickers, including legal recognition, safe working conditions and fair bargaining mechanisms. In practice however, we find that formalisation policies take significantly different forms from one country to another and often fail to provide these benefits.