It is located at the confluence of the Auglaize and Maumee rivers about 55 miles (89 km) southwest of Toledo and 47 miles (76 km) northeast of Fort Wayne, Indiana, in Ohio's northwestern corner.

[5] The city contains the site of Fort Defiance, built by General "Mad" Anthony Wayne in August 1794 during the Northwest Indian War.

Wayne surveyed the land and declared to General Charles Scott, "I defy the English, Indians, and all the devils of hell to take it.

[7] Today a pair of cannons outside the city library on the Maumee River overlook the confluence and mark the location of Fort Defiance, along with a mounded outline of the fort walls.

Historical plaques in the sidewalks mark the full extent of Fort Winchester.

[10] Defiance lends its name to a distinct end moraine from the Wisconsin glaciation.

As Cushing et al. point out, "The Defiance moraine represents the last notable stand of the glacial front in this region."

The moraine varies in width from 2 to 4 miles [3.2 to 6.4 km], and according to Leverett, "it is like a broad wave whose crest stands 20 to 50 feet [6.1 to 15.2 m] above the border of the plain outside it.

[17] The 2018-2022 U.S. Census Bureau American Community Survey (ACS) median income for households (in 2022 dollars) was $58,750.

29.4% of all households were made up of individuals, and 11.5% had someone living alone who was 65 years of age or older.

27.6% of all households were made up of individuals, and 10.3% had someone living alone who was 65 years of age or older.

Defiance has several city parks that offer a variety of recreational activities, including baseball and softball diamonds, as well as playground equipment.

The park provides picnic facilities, nature trails, and fishing.

Schools maintained by local Lutheran and Catholic churches also provide preschool-grade 8 education.

Defiance College is a member of the NAIA and can give scholarships out to its athletes.