The challenge of transitioning from a linear to a circular economy model is still ongoing and requires the development and application of new knowledge, leading to innovative, technological, and sustainable processes, products, and services. The evolution of global research on this topic from 2004 to 2019 was studied in this work. For this purpose, a bibliometric analysis of 1366 articles was applied, producing results on the scientific productivity of the driving agents that most contribute to this theme. The findings show a growing interest, especially in the last four years, in the study of circular economy (CE) policies on the environment. The main subject area that articles address is environmental science. Five research lines have been identified, which mainly study the efficient management of energy resources and the economic factors that make the CE model possible: Environmental pollution and agricultural activity; waste management to avoid a negative environmental impact; improvement of the environmental impact through ecological products; the product life cycle, and the consequences of climate change. The implementation of CE policies will contribute to making economies less dependent and unprotected and more competitive. Global research has exhibited an upward trend during the period analyzed and has grown exponentially since 2015, coinciding with the publication of the Sustainable Development Goals (SDGs) of the 2030 Agenda.