Common heritage of humanity is a principle of international law that holds the defined territorial areas and elements of humanity's common heritage (cultural and natural) should be held in trust for future generations and be protected from exploitation by individual nation states or corporations. Some possible examples include global communication between individuals over the internet and geostationary orbit over the high seas.

It is also termed the common heritage of mankind, common heritage of humankind or common heritage principle.

In tracing the origins of the common heritage principle, it is important to distinguish its history as a term from its conceptual history. The common heritage principle was developed under different names, including common "heritage", common "property", and common "patrimony" of mankind. These terms have at times described different concepts; for instance, in 1813 the "property of mankind" might mean the arts and sciences, rather than items or areas. By the early 20th century, "common heritage" and similar terms usually referred to areas and the resources in them, while other referents had become known under terms like "cultural heritage of all mankind", such as in the preamble to the 1954 Hague Convention for the Protection of Cultural Property in the Event of Armed Conflict.

Conceptually, the common heritage arose in response to the Roman civil law principle of res communis, which described items or areas that anyone could access or use, but none could own. Common heritage instead described areas or items that were owned by humanity as a collective. For example, in his essay Toward Perpetual Peace, Immanuel Kant claimed that the expansion of hospitality with regard to "use of the right to the earth's surface which belongs to the human race in common" would "finally bring the human race ever closer to a cosmopolitan constitution".

The first known use of Common Heritage of Mankind by a state representative in the United Nations, constituting state practice, was at the First UN Conference on the Law of the Sea by Prince Wan Waithayakon of Thailand in 1958. The role of 'mankind' as a legal subject was mentioned in negotiations for the 1967 Outer Space Treaty, and mentions of 'mankind' appear across the space treaties. 'Mankind' as a subject in international law also appears in the Preamble of the United Nations Charter, the Preamble of the North Atlantic Treaty (1949) and the Treaty on the Non-Proliferation of Nuclear Weapons (1968).

In 1970, United Nations General Assembly Resolution 2749, the Declaration of Principles Governing the Seabed and Ocean Floor, was adopted by 108 nation states and stated that the deep seabed should be preserved for peaceful purposes and is the "Common Heritage of Mankind."

In 1982, the Common Heritage of Mankind concept was stated to relate to "the seabed and ocean floor and subsoil thereof, beyond the limits of national jurisdiction" under Article 136 of the United Nations Law of the Sea Treaty (UNCLOS).

In his book titled Cries of the Sea: World Inequality, Sustainable Development and the Common Heritage of Humanity, Payoyo argues that the common heritage of humanity principle in Part XI of the Law of the Sea Treaty should favour developing states who were the voice of conscience in establishing it, and not merely in some transient 'affirmative action' manner. He claims, however, that the 1994 Implementation Agreement facilitated control by industrialised countries of the International Seabed Authority (ISA), allowing access by the private sector to the deep sea bed and inhibiting constructive dialogue on sustainable development.