Wood was born in Cedar Rapids, Iowa, the middle of three children born to Warren and Debbie Wood; he has English, Irish, German and Polish ancestry and was raised a Catholic. He was nicknamed Elijah "Spark Plug" because he was a maniacally energetic child. He has a brother, Zack, a video game producer and seven years his senior, as well as sister, Hannah, younger by three years who is a poet and actress and has had small roles in a number of his films.

A professional actor since the age of nine, Wood is best known for the role of Frodo Baggins in the Lord of the Rings trilogy. He took the stage in his elementary school's rendition of the play The Sound of Music. The following year, he graduated to the title character of The Wonderful Wizard of Oz. Wood also served as choir boy during the production of See How They Run, produced by the Marion Creative Council.

Making his film debut with a minor part in Back to the Future II in 1989, Wood landed a succession of subsequent larger roles and became a critically acclaimed child actor. His performance in The War gained him a nomination by the YoungStar Awards (for which he was nominated five times and won once), and Roger Ebert said in his review of the film that "Elijah Wood has emerged, I believe, as the most talented actor in his age group in Hollywood history."

His role as Frodo in The Lord of the Rings made him a star, but he has thus far resisted typecasting by recently choosing less sympathetic roles, such as a stalker in Eternal Sunshine of the Spotless Mind and a mute cannibal in Sin City.

Wood recently won the role of a young Iggy Pop in a yet-to-be-filmed biographical account of the rock-star.