Keaʻau (also written as Keaau) is a census-designated place (CDP) in Hawaiʻi County, Hawaii, United States located in the District of Puna. The population was 2,010 at the 2000 census. The population increased by 12.1% to 2,253 at the 2010 census.
Keaʻau is on the east side of the island of Hawaiʻi at 19°37′16″N 155°2′30″W (19.621072, -155.041706). It is bordered to the southwest by Kurtistown. Hilo is 8 miles (13 km) to the north. The junction of Hawaii Route 11 (the Hawaii Belt Road) and Hawaii Route 130 (Keaau-Pahoa Road) is in the northern part of the community. According to the United States Census Bureau, the CDP has a total area of 2.6 square miles (6.7 km2), all of it land.
The Board on Geographic Names officially designated the populated place as Keaʻau in 2003.
At the 2010 census there were 2,253 people in 701 households residing in the CDP. The population density was 901.2 people per square mile (352.0/km2). There were 757 housing units at an average density of 302.8 per square mile (118.3/km2). The racial makeup of the CDP was 12.38% White, 0.22% African American, 0.18% American Indian & Alaska Native, 52.02% Asian, 7.50% Native Hawaiian & Pacific Islander, 0.44% from other races, and 27.25% from two or more races. Hispanic or Latino of any race were 8.74%.
Of the 701 households, 28.0% had children under the age of 18 living with them.