With his wife, Hannah Nydahl (1946-2007), he founded Diamond Way Buddhism, a worldwide Karma Kagyu Buddhist organization with over 600 centers for lay practitioners.

Nydahl is the author of more than twenty books (in German and English) about Diamond Way Vajrayana Buddhism, with translations into multiple languages.

Growing up in Denmark during the second world war, Nydahl witnessed his parents working in the Danish resistance movement, helping transport Jews to neutral Sweden.

[2][3] In the early 1960s, he served briefly in the Danish Army,[4] then studied philosophy, English, and German at the University of Copenhagen, where he completed the examen philosophicum with the best possible grade.

[5] As a young man, Nydahl was involved in boxing, motorcycles, race car driving and also travelled overland from Denmark to Nepal several times.

[8] During this time the Nydahls also became students of Mipham Chokyi Lodro, the fourteenth Shamarpa, the 3rd Jamgon Kongtrul, and Kalu Rinpoche in Sonada.

[9][10] Upon returning to Europe in 1972, the 16th Karmapa asked Hannah and Ole Nydahl to begin teaching Buddhism and organize meditation centers,[11] first in their native Denmark, then in Germany and other countries.

Until 2013, Nydahl taught conscious dying or phowa, as well as other Buddhist meditation practices, but in recent years he has been focused on giving Mahamudra; teachings on the nature of mind.

[9] Together with his students, Nydahl has created Buddhist centers that provide access to Vajrayana meditation methods without requiring an understanding of Tibetan language or culture.

Ole Nydahl believes it essential for people to understand and read the meditations in their own language in order for Buddhism to become truly rooted in the West, as noted in the preface to the meditation booklet titled Refuge and the Enlightened Attitude, used in Diamond Way Buddhist Centers, in which Nydahl states, "This practice used to have an exotic edge because the repetition was in Tibetan.

A non-profit international foundation under German law, it supports projects worldwide, such as a library in Karma Guen (Malaga, Spain), which translates and preserves Buddhist texts; organizes cultural events such as Tibetan art exhibitions; and is responsible for building retreat centers and stupas in Europe and Russia.

"[37] Martin Baumann, a professor of religion at the University of Lucerne,[38] remarked in a newspaper interview "when I listen to his [Nydahl's] alarmingly superficial formulations in his talks I can understand his critics who say that he is presenting a watered-down 'instant Buddhism', a sort of 'Buddhism light' for the West.

[47] He regrets that Nydahl's ideas are not discussed by Tibet scholars, and opines that they have a duty to counterbalance the prevailing negative criticism by sociologists and students of New Religious Movements.

Because Shamar Rinpoche was one of Hannah and Ole Nydahl's main teachers, they supported his recognition of Trinley Thaye Dorje as the 17th Karmapa.

"[48] It was largely because of the work of Hannah and Ole Nydahl that most European Karma Kagyu centers chose to support Trinley Thaye Dorje.

[49] Due to his role in the Karmapa controversy, Nydahl has been heavily criticized by the supporters of Ogyen Trinley Dorje, such as the authors Mick Brown and Lea Terhune, a student of Tai Situpa.

[50] In connection to this, some blame Nydahl for causing the 1992 split of the Karma Kagyu, and accuse him of breaking the samayas to his teachers, which is deprecated in Vajrayana.

[51] Some members of the press have criticized Nydahl's version of Diamond Way Buddhism, describing it as featuring "prevalent militaristic appearances, right-wing political views and fierce anti-Islam rhetoric".

This addresses his legitimization narrative of himself as emanation of a Buddhist protector and his Kālacakra-linked fierce interpretation of Islam in particular as a key threat to Western freedom and human, especially women's rights.

On 31 August 2019 Ole Nydahl and Anne Behrend were married at the Diamond Way Buddhist center in Těnovice, Czech Republic.