The literature on circular ecosystems is growing rapidly, given the potential that ecosystems offer in achieving resource circularity. However, the diversity of research streams on circular ecosystems makes discussions disconnected, which may hinder the understanding of the field and the identification of research opportunities that still need to be explored. Therefore, this study relies on a systematic literature review to identify the current key areas of research from an empirical perspective. This identification is important to understand which topics are emerging and gaining relevance in the field. As a result, four main research areas were identified: (1) Circular ecosystem structure and functioning; (2) Circular ecosystem orchestration and management; (3) Circular ecosystem innovation and strategies; and (4) Circular ecosystem digital transformation. Each area are not independent, but mutually interconnected, providing complementary contributions for understating the circular ecosystem phenomenon. As a major contribution, this paper proposes an integrated model based on the four research areas, consolidating the knowledge established in the field so far. Additionally, it presents a future research agenda with twenty guiding questions to help expand the current contributions across the four main research areas. This study has implications not only for understanding what has already been explored related to circular ecosystems, but also for identifying opportunities for future investigation.