Steuben County is northernmost county in the U.S. state of Indiana. As of the 2020 United States census the county population was 34,435. The county seat (and only incorporated city) is Angola. Steuben County comprises the Angola, IN Micropolitan Statistical Area.

After the American Revolutionary War established US sovereignty over the territory of the upper midwest, the new federal government defined the Northwest Territory in 1787 which included the area that is present-day Indiana. In 1800, Congress separated Ohio from the Northwest Territory, designating the rest of the land as the Indiana Territory. President Thomas Jefferson chose William Henry Harrison as the governor of the territory, and Vincennes was established as the capital. After the Michigan Territory was separated and the Illinois Territory was formed, Indiana was reduced to its current size and geography. By December 1816, the Indiana Territory was admitted to the Union as a state.

This area was historically occupied by the Potawatomi people, one of the tribes in the Council of Three Fires. Typically they lived in highly decentralized bands. Treaties signed by some leaders with United States representatives ceded large areas of their territory to the US. Starting in 1794, Native American titles to Indiana lands were extinguished by usurpation, purchase, or war and treaty. The United States acquired land from the Native Americans in the 1809 treaty of Fort Wayne, by the treaty of St. Mary's in 1818, and in 1826 by the Treaty of Mississinewas, which included the future Steuben County.

The Indiana State Legislature passed an omnibus county bill on February 7, 1835, that authorized the creation of thirteen counties in northeast Indiana, including Steuben. In 1837 the county was organized. It was named for Baron Frederick von Steuben, an officer of the American Revolutionary War. In 1840 the Potawatomi were forcibly removed from this area and neighboring territory in Michigan and Ohio to Indian Territory in Kansas.

A Potawatomi chief, Baw Beese, led a band that was based at what later became known as Baw Beese Lake nearby in Michigan. His daughter Winona married Negnaska and lived in what is now Indiana. She was executed in the 1830s by her husband's people after she killed Negnaska for selling her pony. Winona's husband had pledged his rifle to Aaron B. Goodwin of Fremont for the use of a 5-gallon keg. The Indians had the keg filled with whiskey at Nichols' store in Jamestown, and he took all the money they had. Negnaska sold his wife Winona's pony in order to pawn his rifle. Winona owned the pony outright, either as a gift from her father or having bought it with her own money. She killed Negnaska in anger for selling what was hers. Winona was held by the tribe for a few hours until her husband's nearest relative arrived to execute her. As was their custom, he stabbed her to the heart as she had her husband.

John D. Barnard and Sheldon Havens encountered the Potawatomi group after the execution; they helped them move the bodies to a nearby grave that had been dug. The Indians did not bury the bodies until after the white men were out of sight. But Dr. B.F. Sheldon found out about it and exhumed the bodies for dissection a few days later, outraging the mourning Potawatomi. About two weeks later some Potawatomi returned the keg to Goodwin and tried to retrieve Negnaska's rifle, but Goodwin pretended not to know the man had been killed and refused to release the rifle to his friends.

The county's low rolling hills have been largely cleared and leveled for agricultural use, although the drainage areas are still wooded. The highest point (1,200 feet/370 meters ASL) is a hillock one mile (1.6 km) east of Glen Eden.

The county contains a state park and 105 lakes of various sizes. Some of the larger lakes are Lake James, Lake George, Clear Lake, Jimmerson Lake, Lake Gage, and Crooked Lake.