Grundy County was formed on January 15, 1851, and became self-governing in 1856. It was named after Felix Grundy of Tennessee, a statesman, Senator, member of the House of Representatives and Attorney General under President James K. Polk.
The first courthouse was built in 1861. The wooden, two-storey building contained a courtroom, but was used for other purposes, including housing the office of the sheriff, county treasurer, the judge, as well as a chamber for the jury. The cornerstone for a second courthouse was laid on November 11, 1891.