Wood was born on January 28, 1981, in Cedar Rapids, Iowa, the second of three children. His parents, Debbie (née Krause) and Warren Wood, operated a delicatessen. Wood is of Austrian, Danish, English, German, and Polish descent. He was raised Roman Catholic. He has an older brother, Zachariah (born 1974), who is a video game producer at Sony, and a younger sister, Hannah (born October 7, 1983), who is an actress. At age seven, Wood began modeling in his hometown and took piano lessons. In elementary school, he appeared in The Sound of Music, followed by the title character in The Wonderful Wizard of Oz. He also served as choir boy in a Marion Creative Council production of See How They Run. In 1989, his parents sold their delicatessen and the family–without his father–moved to Los Angeles for Wood to pursue an acting career. His parents divorced when he was 15.
Wood modeled and did local commercials. He got his first break in the video for Paula Abdul's "Forever Your Girl", directed by David Fincher. This was followed by a pivotal role in the TV film, Child in the Night, and a minor role in Back to the Future Part II. Nine-year-old Wood auditioned for a role in Kindergarten Cop, but was told by director Ivan Reitman that his performance was not believable, which Wood later said was "a harsh thing to say to a nine-year-old". Playing Aidan Quinn's son in Avalon and Tin Men garnered professional attention for Wood; Avalon received widespread critical acclaim and was nominated for four Academy Awards. A small part in Richard Gere's Internal Affairs was followed by the role of a boy who brings estranged couple Melanie Griffith and Don Johnson back together in Paradise (1991). Wood co-starred with Mel Gibson and Jamie Lee Curtis in Forever Young (1992) and Joseph Mazzello in Radio Flyer.
In 1993, Wood played the title character in The Adventures of Huck Finn, and appeared in The Good Son; The following year, he starred in The War. The latter film was nominated for four awards and won two. Roger Ebert's film review praised Wood highly, stating that Wood "has emerged, I believe, as the most talented actor, in his age group, in Hollywood history".
Wood's title role in North was followed by a Super Bowl commercial for Wavy Lay's potato chips (with Dan Quayle). In 1995, Wood was in the video for The Cranberries "Ridiculous Thoughts", played the lead role in Flipper, and was in Ang Lee's critically acclaimed, The Ice Storm. In 1997, Wood was Jack "The Artful Dodger" Dawkins in Tony Bill's film adaptation of Oliver Twist, and had a leading role in Deep Impact, and supporting one in The Faculty. In 1999, Wood played a suburban white teenager who affects hip-hop lingo in James Toback's Black and White, and a junior hitman in Chain of Fools.
Wood was cast as Frodo Baggins in The Lord of the Rings: The Fellowship of the Ring, the first installment of director Peter Jackson's adaptation of J. R. R. Tolkien's multi-volume novel. This gave Wood top billing as Baggins, alongside a cast that included Ian McKellen, Liv Tyler, Orlando Bloom, Cate Blanchett, Christopher Lee, Sean Bean, Sean Astin, Billy Boyd, Dominic Monaghan, Viggo Mortensen, and John Rhys-Davies. The Lord of the Rings trilogy was filmed in New Zealand, in a process taking more than one year for principal photography alone, with pick-up shots occurring annually for the next four years. Before the cast left the country, Jackson gave Wood two gifts: one of the One Ring props used on the set and Sting, Frodo's sword. He was also given a pair of prosthetic "hobbit feet" of the type worn during filming.
In 2002, Wood lent his voice to the direct-to-video release of The Adventures of Tom Thumb and Thumbelina. The second part of Peter Jackson's trilogy was also released, titled The Lord of the Rings: The Two Towers. In 2003, Wood starred in the direct-to-video movie All I Want (also titled Try Seventeen). The Lord of the Rings: The Return of the King was unveiled that December, sweeping the 76th Academy Awards in early 2004.
Wood's first post-trilogy role was in Eternal Sunshine of the Spotless Mind, as a lab technician; he next played the serial killer Kevin in Robert Rodriguez's adaptation of Frank Miller's comic-book series, Sin City. On May 12, 2005, Wood hosted a program called MTV Presents: The Next Generation Xbox Revealed when the new Xbox 360 games console was launched.
In 2005, Wood starred in Everything Is Illuminated, in which he plays a young Jewish-American man on a quest to find the woman who saved his grandfather during World War II. It was based on the novel of the same name by Jonathan Safran Foer. In Green Street, he played an American college student who falls in with a violent English football firm. Both had limited release but were critically acclaimed.
Wood shot a small part in Paris, je t'aime, which consists of 18 five-minute sections, each directed by a different director. Wood’s section, called "Quartier de la Madeleine", was directed by Vincenzo Natali. The film opened on May 18 at the 2006 Cannes Film Festival and was shown at 2006 Toronto International Film Festival. First Look Pictures acquired the North American rights, and the film opened in the US in early 2007.
In 2006, he was part of the ensemble cast of Emilio Estevez's Bobby, in which his character marries Lindsay Lohan's character to change his draft classification. The film premiered at the Venice Film Festival and was released theatrically on November 17, 2006.
In Happy Feet, Wood provided the voice of Mumble, a penguin who can tap dance, but not sing. Happy Feet was released on November 17, 2006, and has grossed over $380 million worldwide. The movie also received a Golden Globe Award nomination and won an Academy Award and a BAFTA for Best Animated Feature. Day Zero, a drama about the draft in the United States, had its debut at the 2007 Tribeca Film Festival. Wood portrays draftee Aaron Feller.
In 2006, Wood hosted the special Saving a Species: The Great Penguin Rescue for Discovery Kids Channel; he was nominated for a Daytime Emmy in the category of acting in a children/youth/family special. On January 4, 2007, Wood joined Screen Actors Guild President Alan Rosenberg to announce the nominees for the 13th Annual Screen Actors Guild Awards.
In The Oxford Murders, a film adaptation of the novel of the same name by Guillermo Martínez, Wood plays a graduate student who investigates a series of bizarre, mathematically-based murders in Oxford. It was released in Spain on January 18, 2008. Wood also voiced the lead in the animated feature film version of the short film 9. A project in which Wood was set to star, a biographical film about singer Iggy Pop, putatively named The Passenger, has not come to fruition after years in development.
Wood's first starring TV role is on the FX series, Wilfred, in which he plays Ryan Newman. The pilot was shot in the summer of 2010. In January 2011, it was confirmed that Wood would reprise the role of Frodo Baggins in The Hobbit: An Unexpected Journey, the first film of The Hobbit trilogy, released on December 14, 2012.
In 2012, Wood appeared in the psychedelic and dreamlike Flying Lotus music video "Tiny Tortures," where he appears as a recent amputee coming to grips with his new situation.
At PAX East in April 2012, it was confirmed that Wood would give the voice to Agent Maine's AI, Sigma, in Season 10 of the machinima series Red vs. Blue. Wood also starred in the Beastie Boys' music video for "Make Some Noise", along with Seth Rogen and Danny McBride.
In 2013, Wood starred in Grand Piano (Director: Eugenio Mira, Writer: Damien Chazelle).
Since 2016, Wood has been co-starring with Samuel Barnett as Todd Brotzman in the BBC America series Dirk Gently's Holistic Detective Agency.
In 2005, Wood started his own record label called Simian Records. On September 19, 2006, Wood announced that Simian had signed The Apples in Stereo as their first band, with their new album New Magnetic Wonder released in February 2007. In addition, he also directed the music video for "Energy". The other band signed to Simian thus far is Heloise and the Savoir Faire.
In 2006, Wood was also in Season 2 Episode 6 of American Dad!. He was the voice of Ethan, a college student and Haley's crush, who listens to Professor Baxter's (Roger) advice about following your heart and doing something new. Ethan takes this the wrong way and stabs his father 38 times (not shown) and becomes very crazy. Roger admits to being a fake, and he and Hayley leave, saying that the police are coming. This suggests that Ethan gets arrested, and is out of the show. Wood does not appear again.
Wood has also provided voiceovers for video games, providing the voice for Spyro the Dragon in the Legend of Spyro game trilogy, as well as reprising Mumble in the game version of Happy Feet. He also contributed his talents to fellow Lord of the Rings star Viggo Mortensen's album Pandemoniumfromamerica, singing and playing various instruments on the album.
On April 11, 2008, Wood was the guest host of Channel 4's Friday Night Project. On April 25, 2009, Wood was honored with the Midnight Award by the San Francisco International Film Festival as an American actor who "has made outstanding contributions to independent and Hollywood cinema, and who brings striking intelligence, exemplary talent and extraordinary depth of character to his roles". Wood also starred in an episode of Yo Gabba Gabba!, entitled "Eat," where he danced and "went crazy" alongside the rest of the Yo Gabba Gabba! cast. Wood can be seen in a short film on stepthroughtheportal.com. The site is an interactive website created by Simian Records artists The Apples in Stereo, promoting their upcoming album, Travelers in Space and Time.
In addition to producing and acting, Wood has become a well-known DJ. Together with his friend Zach Cowie, they formed Wooden Wisdom and has toured around the world. They have spun at events such as the Bushmills Live 2012 festival at the Old Bushmills Distillery, the opening of the Brickell City Centre and at the pre-Emmy party at The London West Hollywood hotel.
Despite the common misconception, Wood has confirmed that his DJ name is just his name, and not "DJ Frodo" as has been falsely spread by the internet.
Wood has signed up to co-produce and also star in the film Black Wings Has My Angel, based on the noir novel of the same name, with Anthony Moody and Rob Malkani of Indalo Productions. Wood, alongside Tom Hiddleston and Anna Paquin, started shooting in late 2012.
In 2010, Wood, together with Daniel Noah and Josh C. Waller, founded The Woodshed, a production company that promotes horror films. In 2013, the company was re-branded as SpectreVision. In 2010, Wood starred in the web series 'Red vs Blue as the A.I. fragment Sigma.
In 2010, Wood also starred alongside Lemmy and Selma Blair in the short film/music video Full of Regret for Canadian rock band Danko Jones.
Wood also stars in the TV show Wilfred and voiced Shay, one of two main characters in the adventure game Broken Age for which he won the 2014 Performance in a Comedy, Lead by National Academy of Video Game Trade Reviewers (NAVGTR). In 2014, Wood provided the voice of Wirt in Over the Garden Wall, a miniseries on Cartoon Network.
Wood's most dedicated charitable commitment is to The Art of Elysium that therapeutically helps hospitalized children deal with their ailments by concentrating on creating art. He has been involved with the organization since 2008 and received their Spirit of Elysium Award in 2012 for his continued support with the charity.
Wood has supported campaigns such as Keep a Child Alive, ALDO/YouthAIDS, Make a Film Foundation and TOMS Shoes among other civil, political and environmental causes. Fellow actor Liev Schreiber, who directed Wood in Everything Is Illuminated, commented that Wood has a "generosity of spirit" and a "sincere goodness as a human being".
On April 23, 2010, in a charitable gesture, Wood visited the town of Curepto, Chile, one of the hardest hit by the 8.8 magnitude earthquake that struck Chile on February 27, 2010. He made personal visits to many of the victims and was accompanied by the First Lady of Chile, Cecilia Morel.
In 2013, Wood sold his $1.75 million home in Santa Monica, California, and purchased a $1 million home in the Bouldin Creek neighborhood of Austin, Texas.
Wood is a music lover, owning a collection of roughly 4,000 vinyl records and CDs. He has cited The Smashing Pumpkins as his favorite band.
Wood has a tattoo of the number nine written in the Sindarin language, which uses the Tengwar script, and in the English language (rather than Quenya as is widely believed), below his waist on the right side. It refers to his character as one of the Fellowship of the Ring. By coincidence, he had a voice role in a film titled 9. The other actors of "The Fellowship" got the same tattoo, with the exception of John Rhys-Davies, whose stunt double got the tattoo instead.
In May 2006, Autograph Collector Magazine published its list of 10 Best & 10 Worst Hollywood Autograph Signers; Wood was ranked #7 of Best Signers.
In 2008, during an appearance on Jack Osbourne's show Adrenaline Junkie, he became the first person to cross Victoria Falls on ropes.
Wood supported 2016 presidential candidate Bernie Sanders.
Wood is a fan of the podcast My Dad Wrote a Porno and appeared on an episode of the podcast in 2016.
In 2016, Wood spoke of his belief that organized child sexual abuse is prevalent in the Hollywood film industry.