Buddhism in the West (or more narrowly Western Buddhism) broadly encompasses the knowledge and practice of Buddhism outside of Asia, in the Western world. Occasional intersections between Western civilization and the Buddhist world have been occurring for thousands of years. Greek colonies existed in India during the Buddha's life, as early as the 6th century. The first Westerners to become Buddhists were Greeks who settled in Bactria and India during the Hellenistic period. They became influential figures during the reigns of the Indo-Greek kings, whose patronage of Buddhism led to the emergence of Greco-Buddhism and Greco-Buddhist art.

There was little contact between the Western and Asian cultures during most of the Middle Ages, but the early modern rise of global trade and mercantilism, improved navigation technology and the European colonization of Asian Buddhist countries led to increased knowledge of Buddhism among Westerners. This increased contact led to various responses from Buddhists and Westerners throughout the modern era. These include religious proselytism, religious polemics and debates (such as the Sri Lankan Panadura debate), Buddhist modernism, Western convert Buddhists and the rise of Buddhist studies in Western academia.

During the 20th century, there was growth in Western Buddhism due to various factors such as immigration, globalization, the decline of Christianity and increased interest among Westerners. The various schools of Buddhism are now established in all major Western countries making up a small minority in the United States (1% in 2024), Europe (0.3% in 2020), as well as in Australia (2.4% in 2016) and New Zealand (1.5% in 2013).

The first contact between Western culture and Buddhist culture occurred during Alexander the Great's conquest of India.

After Alexander's conquest, Greek colonists established cities and kingdoms in Bactria and India where Buddhism was thriving. This cultural interaction saw the emergence of Greco-Buddhism and Greco-Buddhist art, especially within the Gandharan civilization which covered a large part of modern-day northern Pakistan and eastern Afghanistan. Greek sculptors in the classical tradition came to teach their skills to Indian sculptors resulting in the distinctive style of Greco-Buddhist art in stone and stucco seen in hundreds of Buddhist monasteries which are still being discovered and excavated in this region.

Greco-Buddhism was an important religion among the Greco-Bactrians and the Indo-Greeks. The Indo-Greek kings such as Menander I (165/155 –130 BCE) and Menander II (90–85 BCE) used Buddhist symbolism in their coins. Menander I is a main character of the Indian Buddhist scripture known as Milinda Panha ("The Questions of King Milinda"), which states that he adopted the Buddhist religion. The Buddhist tradition considers Menander as a great benefactor of the Dharma, along with Ashoka.

The Mahavamsa mentions that during Menander's reign, a Greek elder monk named Mahadharmaraksita led 30,000 Buddhist monks from "the Greek city of Alexandria" (possibly Alexandria on the Caucasus) to Sri Lanka for the dedication of a stupa showing that Greeks took an active part in Indian Buddhism during this period.

Greco-Buddhist styles continued to be influential during the Kushan empire.