The original name of Woodbury County was Floyd County, in honor of Sergeant Charles Floyd of the Lewis and Clark Expedition. He died of an illness and was the first white man buried in Iowa. Floyd was then replaced by Wahkaw County when the county was established in 1851. The county was established in 1851 as one of 50 new counties organized by the Legislature. The first county seat of Wahkaw County was Thompsonville, a small village set up by the early settler William Thompson. It never really developed and the village eventually disappeared.

Woodbury County became the official name on January 12, 1853 in honor of Levi Woodbury, governor of New Hampshire, U.S. senator and Secretary of Navy and Treasury.

In 1853 the Legislature chose the town of Sergeant's Bluff as the first county seat of Woodbury County. The county elections were then held in the home of William Thompson, 17 votes were cast, and the offices were kept in the homes of the officials.

In the spring of 1856 a vote was taken to relocate the county seat. Sioux City, which was platted in 1854, beat out the towns of Sergeant's Bluff and Sergeant's Bluff City.

In 1857 a contract was awarded for the construction of the first courthouse of Woodbury County, but for some reason the contract was canceled, and the county offices remained scattered.

Later in 1857 the county voted to authorize a $75,000 bond issue for a courthouse. The first courthouse of the county was completed in 1858 at cost of $70,000. It was three stories high and was constructed of brick.

This building was used until 1914, when it was decided that the population had outgrown it, and a new one was needed. The county approved more than $500,000 for the new courthouse and later decided to sell the old building and property. The cornerstone was laid on July 10, 1916, and the construction was completed on March 1, 1918. The building consists of Roman brick and granite and is beautifully decorated with sculptures over the doors and on the 157-foot-tall tower rising from the middle of the building. Around $400,000 was spent on the restoration of the building, and in 1973 the building was included on the National Register of Historic Places.