Supporting older people’s use of sustainable transport is important for both population health and sustainable development, especially in the context of global population ageing. This systematic review identifies individual and environmental factors that influence older people’s sustainable transport use and synthesises findings using a framework approach. Factors influencing older people’s walking (n = 10 studies), bus use (n = 11), community transport use (n = 1), bicycling (n = 1), and e-bicycling (n = 1) were found to be physical, geographical, facility-based, economic, time-based, fear-based, space-based, information-based, or interpersonal. Many factors were common across transport modes. One reason for this is that environmental features designed to facilitate the use of one particular transport mode also influenced the use of other modes (e.g., bus shelters influence not only bus use but also walking as they provide pedestrian seating). Thus, environments need to be considered from the perspective of multiple, different types of road users. Another reason is that many factors related to the ways individuals experienced their environment (e.g., finding information guiding behaviour in public spaces to be unclear), regardless of any specific transport mode. This review highlights the important need for greater cross-sectoral action and input from older people.