Garner was born on November 22, 1868, in a log cabin near Detroit in Red River County to John Nance Garner II and his wife, Sarah Guest Garner. The mud-chinked log cabin that Garner was born in no longer exists but the house that he grew up in survives and is located at 260 South Main Street in Detroit, Texas. It is a large, white, two-story house. Garner attended Vanderbilt University in Nashville, Tennessee, for one semester before dropping out and returning home. He eventually studied law, was admitted to the bar in 1890, and began practice in Uvalde, Uvalde County, Texas.