The Hindu guru, whose real name is Jagdish Vasudev, posted an emotional video message from Tibet on his social media accounts, with several million followers.
Some 77 pilgrims were at the Nepal-China border immigration office when the flood hit on Wednesday, he said in a post alongside a terrifying clip of a surveillance video from the Chinese side of the frontier, when a wall of mud and debris crashed over the border building.
The pilgrims were part of several Hindu groups organised by Isha Foundation of Sadhguru, who had been visiting the snow-capped Mount Kailash in Tibet, sacred also to Tibetan Buddhists.
"Literally, the entire group was there in the building, this is a terrible and extraordinary event," he said, as anguished wails from other pilgrims with him are heard over the video.
"All phones are off, telecommunications are down, roads are blocked, we are unable to go there," he said, tears in his eyes.
The tsunami-like rumble of water and mud was caused by a glacial collapse that sent a flow of debris engulfing the valley.
"We have no any official information... but looking at the scale of destruction, it looks bad," Sadhguru said.
"The same building where we were for the immigration just a week ago, that entire building is washed away, and part of the town is washed away."
The pilgrimage to Kailash and Lake Mansarovar is organised annually by India's foreign ministry with Chinese authorities.
It restarted in 2025 for Indians for the first time since the 2020 clash.