Abstract Förster resonance energy transfer (FRET)–based sensing has been steadily gaining popularity in the areas of biochemical analysis, environmental monitoring, and disease diagnosis in the past 20 years. Two-dimensional (2D) nanomaterials are extensively used as donors and acceptors in the FRET sensing because of their attractive optical and chemical properties. In this review, we first present the FRET theory and calculations to give readers a better understanding of the FRET phenomenon. Then, we discuss the recent research advances in using 2D nanomaterials as donors and acceptor in FRET sensing. Finally, we summarize the existing challenges and future directions of 2D nanomaterials in the FRET sensing applications.