Greco-Buddhism, or Graeco-Buddhism, is the cultural syncretism between Hellenistic culture and Buddhism, which developed between the 4th century BCE and the 5th century CE in Gandhara, in present-day north-western Pakistan and parts of north-east Afghanistan.

It was a cultural consequence of a long chain of interactions begun by Greek forays into India from the time of Alexander the Great. A few years after Alexander's death, the Easternmost fringes of the empire of his general Seleucus were lost in a war with the Mauryan Empire, under the reign of Chandragupta Maurya. The Mauryan Emperor Ashoka would convert to Buddhism and spread the religious philosophy throughout his domain, as recorded in the Edicts of Ashoka. This spread to the Greco-Bactrian kingdom, which itself seceded from the Seleucid empire. Within its borders, the Greek fondness for statuary produced the first statues of the Buddha, leading ultimately to the modern tradition.

Following the collapse of the Mauryan Empire, Greco-Buddhism continued to flourish under the Greco-Bactrian Kingdom, Indo-Greek Kingdoms, and Kushan Empire. Mahayana Buddhism was spread from the Gangetic plains in India into Gandhara and then Central Asia during the Mauryan Era, where it became the most prevalent branch of Buddhism in Central Asia. Mahayana Buddhism was later transmitted through the Silk Road into the Han Dynasty during the Kushan era under the reign of Emperor Kanishka. Buddhist tradition details the monk, Majjhantika of Varanasi, was made responsible for spreading Buddhism in the region by Emperor Ashoka.