Jianzhen was born to a Buddhist family in Yangzhou, Jiangsu Province. His original name was Chunyu. At the age of twenty he traveled to China’s capital Chang'an (modern-day Xi'an) to begin his studies.
In 743 two Japanese envoys, Yoei and Fusho, arrived in Yangzhou to invite Jianzhen, the renowned Buddhist abbot with over 40,000 disciples, to return with them to teach in their country. They had been seeking a suitable master in China for ten years, having been dispatched on their quest in 733. The 55-year-old Jianzhen accepted their invitation.
Jianzhen’s first attempt to cross the East China Sea to Japan with 20 disciples was thwarted by the government. Overseas travel was forbidden by the Tang Empire.
On his second attempt Jianzhen managed to make it to sea with 85 disciples and assistants but his ship was wrecked by strong winds.
Jianzhen’s ship hit the rocks in the Zhoushan Sea during his third attempt.
In 744, Jianzhen made a fourth attempt, intending to embark for Japan in Fuzhou, but was intercepted by government agents in Wenzhou and sent back to Yangzhou.
In 748, during Jianzhen’s fifth attempt, his ship ran into storms and drifted far off course down to the south China island of Hainan. While making his back to Yangzhou, Jianzhen became ill and went blind. His disciple Xiang Yan and a Japanese emissary died.
On October 19, 753, the blind Jianzhen began his sixth crossing, setting out from Longxing Temple in Yangzhou. He traveled on a Japanese ship and finally landed at Kagoshima, Kyūshū, Japan on December 20.
They reached Nara the following spring and were welcomed by the Japanese Emperor. Jianzhen lived in Japan for 10 years and died there in 763 at the age of 76.