Sharing economy connects the human and material resources available to private individuals, companies, and city organizational units in a coherent way. The aim of this article is to present a theoretical and practical approach to the sharing economy in the context of using this approach to increase the ecological security of cities. In the article, the method of literature studies on the sharing economy and ecological security was used as the method of gathering knowledge, and the case study method was used to verify the theoretical assumptions of this concept based on the example of specific projects implemented by Polish cities in this field. Taking into account the social perspective and the possibilities of using modern information technologies, thoughts on the future of cities should be related to the creation of new community strategies, in which the sharing economy can be helpful. The sharing economy offers a number of solutions that are already visible in the development strategy of Polish cities, which contributes to an improvement in the quality of life in terms of ecological security. Some selected examples are presented in this article.