Born in England in 1956, Ajahn Amaro received his BSc. in Psychology and Physiology from the University of London. Spiritual searching led him to Thailand, where he went to Wat Pah Nanachat, a Forest Tradition monastery established for Western disciples of Thai meditation master Ajahn Chah, who ordained him as a bhikkhu in April 1979. He returned to England in October 1979 and joined Ajahn Sumedho at the newly established Chithurst Monastery in West Sussex.

In 1983 he made an 830-mile trek from Chithurst to a new branch monastery, Harnham Vihāra, near the Scottish border. In July 1985, he moved to Amaravati Buddhist Monastery north of London and resided there for many years. In the early 1990s, he started making trips to California every year, eventually establishing Abhayagiri Monastery near Ukiah, Northern California, in June of 1996.

He lived at Abhayagiri until the summer of 2010, holding the position of co-abbot along with Ajahn Pasanno. At that time, he then moved back to Amaravati Buddhist Monastery in England to take up the position of abbot of this large monastic community.