Brandon Routh, the third of four children, was born in Norwalk, Iowa, on October 9, 1979, the son of Catherine (née Lear), a teacher, and Ronald Ray Routh, a carpenter. Brandon Routh's family, which is Methodist, has German, French, English, and Native American ancestry. Brandon Routh grew up in Norwalk, approximately 100 miles (160 km) south of Woolstock, the hometown of George Reeves, the first actor to play Superman on television. During his childhood, Brandon Routh thought a full-time acting career was unrealistic, citing his small-town background. In his spare time, he played the trumpet and the piano. Brandon Routh attended Norwalk High School, where he played sports and participated in music and theatre. He has described himself as a "momma's boy" and not "the most popular kid" during his school years. Brandon Routh has also noted that during his younger years, he was fond of the Superman films and comic books.
Brandon Routh attended the University of Iowa for a year, aspiring to be a writer. During this time, he modelled and acted in order to earn his tuition fee. Brandon Routh has said he was often told that he bore a physical resemblance to Christopher Reeve, who had previously portrayed Superman. His former manager signed him on because of the resemblance, telling him that he thought Brandon Routh would be cast as Superman if there was another film in the series.