Decker is a town in Johnson Township, Knox County, Indiana, United States.

[3] Decker is near the White River, and is well known for the watermelon and cantaloupe produced in the surrounding rural area.

According to the 2010 census, Decker has a total area of 0.18 square miles (0.47 km2), all land.

The racial make-up of the town was 97.6% White, 1.2% African American, 0.8% Asian and 0.4% from two or more races.

20.7% of all households were made up of individuals and 8.7% had someone living alone who was 65 years of age or older.

About 14.3% of families and 21.3% of the population were below the poverty line, including 26.7% of those under the age of eighteen and 20.6% of those 65 or over.

The old high school building was struck by lightning, and subsequently destroyed by fire on July 9, 2024.