Yên Bái (listen) is a city and urban district in Vietnam. It is the capital of Yên Bái Province, in the Northeast region of Vietnam. As of 2003 the district had a population of 78,016. The district covers an area of 58 km².
On 9 February 1930, part of the 4th Regiment of Tonkinese Rifles stationed at Yen Bai mutinied against their French officers in the Yen Bai mutiny. They were suppressed by loyal troops from the same unit. This incident led to widespread disturbances against French rule across northeastern Vietnam during 1930-31.