This white paper explores the potential application of the concept of the "common concern of humankind" as a framework for a new international legally binding instrument for the conservation and sustainable use of marine biological diversity in areas beyond national jurisdiction, currently being negotiated by States under the United Nations Convention on the Law of the Sea, as outlined in United Nations General Assembly Resolution 69/292. It reviews the history of the common concern of humankind concept, its relevance in international treaties and case law, and the potential legal and policy implications of the concept's use in a new marine biodiversity agreement.Although less examined than global principles such as the common heritage of mankind, the common concern of humankind concept has a significant history of use by the international community for global environmental issues. Environmental treaties throughout the 20th century referred to shared global problems using various phrases that foreshadow the common concern of humankind. By the end of the century, the Convention on Biological Diversity (1992) and the United Nations Framework Convention on Climate Change (1992) formally expressed the conservation of biological diversity and "change in the Earth's climate and its adverse effects" as common concerns of humankind, respectively. Most recently, the Paris Agreement (2015) again acknowledged climate change as a common concern.As States negotiate a new legal regime to govern the high seas, this paper suggests that reaffirming the conservation and sustainable use of marine biodiversity in ABNJ as a common concern of humankind-already acknowledged by Parties to the CBD-can emphasize certain key principles of interest to States, namely: intergenerational equity, international solidarity, shared decision making and accountability, and benefit and burden sharing through financial cooperation. Moreover, its use would forge a meaningful, logical, and necessary link between the new instrument, the CBD, and international efforts to combat climate change. This paper seeks to show that the current discussions around marine biodiversity in ABNJ present a unique opportunity for the international community to build on the successes of the recent climate change negotiations and reaffirm the critical value of marine biodiversity for humankind.