Arauco Province is one of three provinces of the Chilean region of Bío Bío. It spans a coastal area of 6,366 km2 (2,458 sq mi) just south of the mouth of the Biobío River, the traditional demarcation between the nation's major natural regions, Zona Central and Zona Sur. The province originally covered the once-independent indigenous territory of Araucanía, but this was afterward divided into four provinces. It is devoted largely to agricultural pursuits. The capital Lebu is situated on the coast about 90 km (56 mi) south of Concepción with which it is connected by rail.

Lebu is a port city and commune in central Chile administered by the Municipality of Lebu. Lebu is also the capital of Arauco Province in Bío Bío Region. It lies on the south bank of the mouth of the Lebu River.