The area was settled by varying cultures of indigenous peoples for thousands of years before European contact.

Within the Timucuan Ecological and Historic Preserve in Jacksonville, archeologists excavated remains of some of the oldest pottery in the United States, dating to 2500 BCE.

[7] At the time Europeans arrived, much of what is now Duval County was controlled by the Saturiwa, one of the region's most powerful tribes.

The area that became Duval County was home to the 16th-century French colony of Fort Caroline and saw increased European settlement in the 18th century with the establishment of Cowford, later renamed Jacksonville.

It was named for William Pope Duval, Governor of Florida Territory from 1822 to 1834.

The Mayor of Jacksonville serves as the chief administrator over all of Duval County.

In 2010, 9.0% of the county's population was foreign born, with 49.5% being naturalized American citizens.

26.50% of all households were made up of individuals and 7.80% had someone living alone who was 65 years of age or older.

[24] According to the Secretary of State's office, Democrats comprise a plurality of registered voters in Duval County.

However, the Republican edge in Duval has lessened somewhat in recent years.

Mitt Romney won an equally narrow margin in 2012 and in 2016, Donald Trump only won the county by fewer than 6,000 votes even as he narrowly carried Florida.

In 2020, Joe Biden, despite losing statewide, broke the 44-year Democratic drought in Duval County, winning by less than four points.

In 2024, the county reverted back to the GOP and Trump won it by less than 2 points.

In 2018, Andrew Gillum, despite losing the election, won Duval by four points, the first time a Democrat had won the county in a gubernatorial election since Steve Pajcic's losing bid in 1986.

Four years later, however, Duval rebounded to vote for Ron DeSantis by over 10 points.

In the Senate elections, Bill Nelson only failed to carry the county in his first bid in 2000, and Lawton Chiles and Bob Graham carried the county in all three of their respective bids.

In 2022, Ron DeSantis won the county in his reelection bid by 12 points.

Duval County is served by the Jacksonville Public Library.