Mahayana is the majority form of Buddhism. Estimates in the reference literature put the East Asian Mahayana at roughly 53 per cent of all Buddhists as of 2010, with Vajrayana at a further 6 per cent, against a world Buddhist population that Pew counted at about 320 million for 2020. If Vajrayana is counted inside Mahayana, as many classifications do, the share approaches three in five.
It prevails in China, Taiwan, Japan, Korea, Vietnam and Singapore, and among the Chinese and Vietnamese diaspora everywhere. Counting it is hard for a reason that is not a defect in the surveys. Religious affiliation in Chinese and Japanese practice is frequently not exclusive and often not registered as membership of anything, so the number of people who visit temples, keep ancestral rites and would nonetheless answer a census question about religion with none is very large. The Japanese figures show the spread: one estimate puts Buddhists at around 46 per cent of the population, while a Japanese social survey puts self-identification below 20 per cent, and the gap is a difference of definition rather than of fact.
Institutionally, Mahayana exists as its schools rather than as itself. Chan and Zen, Pure Land, Nichiren, Tiantai and Tendai, Huayan and the Tibetan schools each have their own temples, ordinations, finances and quarrels. What they share is a canon far larger than the Pali one, a liturgy addressed to buddhas and bodhisattvas who can be appealed to, and the vow.