Alba was born in Pomona, California, to Catherine Louisa (nee Jensen) and Mark David Alba. Her mother has Danish, Welsh, German, English, and French ancestry, while her paternal grandparents, who were born in California, were both the children of Mexican immigrants. She has a younger brother, Joshua. Her third cousin, once removed, is writer Gustavo Arellano.

Alba expressed an interest in acting from the age of five. In 1992, the 11-year-old Alba persuaded her mother to take her to an acting competition in Beverly Hills, where the grand prize was free acting classes. Alba won the grand prize, and took her first acting lessons. An agent signed Alba nine months later. Her first appearance on film was a small role in the 1994 feature Camp Nowhere as Gail. She was originally hired for two weeks but her role turned into a two-month job when one of the prominent actresses dropped out.  Alba appeared in two national television commercials for Nintendo and J. C. Penney as a child. She was later featured in several independent films. She branched out into television in 1994 with a recurring role as the vain Jessica in three episodes of the Nickelodeon comedy series The Secret World of Alex Mack. She then performed the role of Maya in the first two seasons of the television series Flipper. Under the tutelage of her lifeguard mother, Alba learned to swim before she could walk, and she was a PADI-certified scuba diver, skills which were put to use on the show, which was filmed in Australia.  In 1998, she appeared as Melissa Hauer in a first-season episode of the Steven Bochco crime-drama Brooklyn South, as Leanne in two episodes of Beverly Hills, 90210, and as Layla in an episode of Love Boat: The Next Wave. In 1999, she appeared in the Randy Quaid comedy feature P.U.N.K.S.. After Alba graduated from high school, she studied acting with William H. Macy and his wife, Felicity Huffman, at the Atlantic Theater Company, which was developed by Macy and Pulitzer Prize-winning playwright and film director, David Mamet. Alba rose to greater prominence in Hollywood in 1999 after appearing as a member of a snobby high school clique in the Drew Barrymore romantic comedy Never Been Kissed, and as the female lead in the 1999 comedy-horror film Idle Hands, opposite Devon Sawa.  Her big break came when writer/director James Cameron picked Alba from a pool of 1,200 candidates for the role of the genetically engineered super-soldier, Max Guevara, on the Fox sci-fi television series Dark Angel. Co-created by Cameron, the series starred Alba, and ran for two seasons until 2002. Alba earned critical acclaim for her role in the show, receiving a Golden Globe nomination as well as the Teen Choice Award for "Choice Actress" and Saturn Award for Best Actress.  Alba's film roles have included playing an aspiring dancer-choreographer in Honey, and an exotic dancer Nancy Callahan in Sin City, for which she received an MTV Movie Award for "Sexiest Performance." Alba portrayed the Marvel Comics character Sue Storm, the Invisible Woman, in Fantastic Four and its sequel. She also starred in Into the Blue (2005), Good Luck Chuck (2007) and Awake (2007).  Alba hosted the 2006 MTV Movie Awards and performed sketches spoofing the movies King Kong, Mission: Impossible III, and The Da Vinci Code. In February 2008, she hosted the Academy of Motion Picture Arts and Sciences' Science and Technical Awards. Alba has been represented by Brad Cafarelli.  Also in 2008, Alba made her acting transition to the horror-film genre in The Eye, a remake of the Hong Kong original. The film was released on February 1, 2008. Though the film was not well received by critics, Alba's performance itself received mixed reviews. She won a Teen Choice for Choice Movie Actress: Horror/Thriller  and a Razzie Award for Worst Actress-nomination. Later in 2008, Alba starred alongside Mike Myers and Justin Timberlake in The Love Guru.  In 2010, Alba starred in five films. She signed on to star as the lead role in An Invisible Sign of My Own in late 2008'. The movie was filmed in 2008, premiered at the Hamptons International Film Festival, and was later released to theaters in May 2011. She also played Joyce Lakeland, a prostitute in The Killer Inside Me, a film adaption of the book of the same name which co-starred Kate Hudson and Casey Affleck. The film premiered at the Sundance Film Festival. Her second film of the year was the romantic comedy Valentine's Day, directed by Garry Marshall. She portrayed Ashton Kutcher's girlfriend, Morley Clarkson, in the ensemble film that included Julia Roberts, Anne Hathaway, Jessica Biel, Bradley Cooper, and Jennifer Garner, among others. Later that year, she appeared in the action film Machete, and in Little Fockers, reuniting with Robert De Niro who was also in Machete.  In 2011, Alba appeared in the film Spy Kids: All the Time in the World.  In January 2012, Alba and business partner Christopher Gavigan launched The Honest Company, a collection of household goods, diapers, and body care products. The company was valued at $1 billion as of 2014. In 2015, it was estimated that Alba owned 15 to 20 percent of the company. In March 2012, Alba announced that she would be releasing a book, The Honest Life, based on her experiences creating a natural, non-toxic life for her family. The book was published in early 2013 by Rodale and later became a New York Times Best Seller.  Alba's 2013 film projects included comedy A.C.O.D. and animated film Escape from Planet Earth. Alba reprised her roles, Santana in Machete's sequel Machete Kills, and Nancy Callahan in Sin City: A Dame to Kill For, the sequel to 2005's Sin City. Filming for the Sin City sequel started in October 2012 and the film was released in August 2014.  In October 2015, Alba launched a collection of skin care and beauty products called Honest Beauty.

What were those films?
She also played Joyce Lakeland, a prostitute in The Killer Inside Me, a film adaption of the book of the same name