The Diamond Sutra (Sanskrit: Vajracchedikā Prajñāpāramitā Sūtra) is a Mahāyāna (Buddhist) sutra from the genre of Prajñāpāramitā ('perfection of wisdom') sutras. Translated into a variety of languages over a broad geographic range, the Diamond Sūtra is one of the most influential Mahayana sutras in East Asia, and it is particularly prominent within the Chan (or Zen) tradition, along with the Heart Sutra.

A copy of the Tang-dynasty Chinese version of the Diamond Sūtra was found among the Dunhuang manuscripts in 1900 by Daoist monk Wang Yuanlu and sold to Aurel Stein in 1907. They are dated back to 11 May 868. It is, in the words of the British Library, "the earliest dated printed book".It is also the first known creative work with an explicit public-domain dedication, as its colophon at the end states that it was created "for universal free distribution".