Three Oaks is a census-designated place (CDP) in Lee County, Florida, United States. The population was 5,472 at the 2020 census, up from 3,592 at the 2010 census. It is part of the Cape Coral-Fort Myers, Florida Metropolitan Statistical Area.

Three Oaks is located in south-central Lee County at 26°28′4″N 81°47′45″W / 26.46778°N 81.79583°W / 26.46778; -81.79583 (26.467908, -81.795768). It is bordered to the south by the village of Estero and to the west by the San Carlos Park census-designated place. Interstate 75 forms the eastern border of the Three Oaks CDP, with access from Exit 128 (Alico Road) at the northeast corner of the CDP. I-75 leads north 10 miles (16 km) to the eastern side of Fort Myers and south 22 miles (35 km) to the Naples area.

According to the United States Census Bureau, the Three Oaks CDP has a total area of 1.7 square miles (4.3 km), of which 1.6 square miles (4.2 km) are land and 0.05 square miles (0.12 km), or 2.77%, are water.

Historical population

Census	Pop.	Note	%±
2000	2,255		—
2010	3,592		59.3%
2020	5,472		52.3%
U.S. Decennial Census

As of the census of 2000, there were 2,255 people, 749 households, and 650 families residing in the CDP. The population density was 1,739.5 inhabitants per square mile (671.6/km). There were 789 housing units at an average density of 608.6 per square mile (235.0/km). The racial makeup of the CDP was 96.10% White, 0.27% African American, 0.18% Native American, 1.37% Asian, 1.37% from other races, and 0.71% from two or more races. Hispanic or Latino of any race were 4.26% of the population.

There were 749 households, out of which 52.1% had children under the age of 18 living with them, 77.0% were married couples living together, 7.9% had a female householder with no husband present, and 13.2% were non-families. 10.4% of all households were made up of individuals, and 3.7% had someone living alone who was 65 years of age or older. The average household size was 3.01 and the average family size was 3.23.

In the CDP, the population was spread out, with 33.6% under the age of 18, 3.6% from 18 to 24, 32.1% from 25 to 44, 22.1% from 45 to 64, and 8.7% who were 65 years of age or older. The median age was 36 years. For every 100 females, there were 96.8 males. For every 100 females age 18 and over, there were 93.0 males.

The median income for a household in the CDP was $69,911, and the median income for a family was $74,286. Males had a median income of $50,250 versus $30,217 for females. The per capita income for the CDP was $23,997. About 1.0% of families and 1.6% of the population were below the poverty line, including 2.5% of those under age 18 and none of those age 65 or over.