Aguilera was born in Staten Island, New York, to Fausto Wagner Xavier Aguilera, a Sergeant in the U.S. Army at the time and Shelly Loraine Fidler, a teacher of Spanish language. Aguilera's father was born in Guayaquil, Ecuador, while her mother is of Irish descent (Christina's maternal grandmother emigrated from County Clare.) Her father, Fausto, was stationed at Earnest Harmon Air Force Base in Stephenville, Newfoundland, Canada and Japan. Aguilera lived with her father and mother until she was seven years old. When Aguilera's parents divorced, her mother took her, and her younger sister Rachel, to her grandmother's home in Rochester, Pennsylvania, a suburb outside of Pittsburgh. According to both Aguilera and Fidler, her father was very controlling, as well as physically and emotionally abusive. She later wrote about her difficult childhood in the songs "I'm OK" in Stripped, and "Oh Mother" in Back to Basics. Although her father has written to Aguilera, she has ruled out any chance to reunite with him. Since then, Fidler has married a paramedic named Jim Kearns, and changed her name.
As a child, Aguilera aspired to be a singer. She was known locally as "the little girl with the big voice", singing in local talent shows and competitions. According to VH1's Driven, whenever competitors learned they would be up against her in any given week, they would immediately withdraw, prompting insiders to claim it was "like sending a lamb to the slaughter." Her peers soon became jealous of her and would frequently subject her to ridicule, ostracism, and, in one gym class, attempted assault. Acts of vandalism around her house included the slashing of the tires on the family car. Eventually, the family relocated to another suburb in the Pittsburgh area (this time, Wexford) and took to secrecy about Aguilera's talent lest another backlash occur. She attended Marshall Middle School near Wexford and North Allegheny Senior High School until she was later home-schooled.
On March 15, 1990, she appeared on Star Search singing Etta James' "A Sunday Kind of Love", but lost the competition at number 2. Soon after losing on Star Search, she returned home and appeared on Pittsburgh's KDKA-TV's Wake Up with Larry Richert to perform the same song. People remarked that the then ten-year-old "sounded 20."

Throughout her youth in Pittsburgh, Aguilera sang "The Star-Spangled Banner" before Pittsburgh Penguins hockey, Pittsburgh Steelers football and Pittsburgh Pirates baseball games. Her first major role in entertainment came in 1993 when she joined the Disney Channel's variety show The New Mickey Mouse Club. Her co-stars included Justin Timberlake, Britney Spears, Ryan Gosling, and Keri Russell, the show lasted another year until its cancellation. According to the documentary Driven, Aguilera's co-stars called her "the Diva". One of her most notable performances was of Whitney Houston's "I Have Nothing".

At the age of fourteen, Aguilera recorded her first song, "All I Wanna Do", a hit duet with Japanese singer Keizo Nakanishi. In 1997, she represented the United States at the "Golden Stag" International Festival with a two-song set.

In 1998, Aguilera sang the High "E" in full voice (E5) on a cover of Whitney Houston's "Run to You" which she recorded with a tape recorder in her bathroom. She was then selected to record the song "Reflection" for the Disney production of Mulan (1998). Recording "Reflection" led to Aguilera earning a contract with RCA Records the same week. "Reflection" peaked within the top twenty on the Adult Contemporary Singles Chart, and it was nominated for a Golden Globe Award for "Best Original Song" in 1998.

Under the exclusive representation of Steve Kurtz, Aguilera's self-titled debut album Christina Aguilera was released on August 24, 1999. It reached the top of the Billboard 200 and Canadian album charts, selling eight million copies in the U.S. and over twelve million copies worldwide. The album is also included in the Top 100 Albums of All Time list of The Recording Industry Association of America (RIAA) based on US sales.

Her singles "Genie in a Bottle", "What a Girl Wants" and "Come on Over Baby (All I Want Is You)" topped the Billboard Hot 100 during 1999 and 2000, and "I Turn to You" reached #3. According to the album's songwriters, Aguilera wanted to display the range and audacity in her voice during the promotion of the album, and performed acoustic sets and appeared on television shows accompanied only by a piano. She ended the year on MTV's New Year's Special, as she performed and was MTV's first artist of the millennium. At the 2000 Grammys Aguilera received a Best Female Pop Vocal Performance nomination for "Genie in a Bottle" and despite earlier predictions, she won the award for Best New Artist.

Later in 2000, Aguilera first emphasized her Latin heritage by releasing her first Spanish album, Mi Reflejo on September 12, 2000. This album contained Spanish versions of songs from her English debut as well as new Spanish tracks. Though some criticized Aguilera for trying to cash in on the Latin music boom at the time. The album still managed to peak at #27 on the Billboard 200 and number one on the Latin album charts. In 2001, it won Aguilera a Latin Grammy Award for Best Female Pop Vocal Album. The album went Gold in the US and sold 3 million worldwide. She also won the World Music Award as the best selling Latin artist that year. Aguilera also released a Christmas album on October 24, 2000 called My Kind of Christmas. It peaked at #28 on the Billboard 200, and has been certified Platinum in the US. Ricky Martin asked Aguilera to duet with him on the track "Nobody Wants to Be Lonely" from his album Sound Loaded; released in 2001 as the album's second single, which reached #1 on the World Chart.

In 2001, Aguilera, Lil' Kim, Mýa, and Pink were chosen to remake Labelle's 1975 single "Lady Marmalade" for the film Moulin Rouge! and its soundtrack. The single Missy Elliott produced hit number one on the Hot 100 for five weeks and was the most successful airplay-only single in history. It also reached number one in eleven other countries amd earned all four performers a Grammy Award for Best Pop Collaboration with Vocals. Aguilera's appearance in the music video was compared to that of Twisted Sister frontman Dee Snider. The video won two MTV Video Music Awards including Video of the Year in 2001, where Aguilera accepted the award saying, "I guess the big hair paid off."

That year a single emerged into record stores called "Just Be Free", one of the demos Aguilera recorded when she was around fifteen years old. When RCA Records discovered the single, they advised fans not to purchase it. Months later, Warlock Records was set to release Just Be Free, an album which contains the demo tracks. Aguilera filed a breach of contract and unfair competition suit against Warlock and the album's producers to block the release. Instead, the two parties came to a settlement to release the album. Aguilera lent out her name, likeness and image for an unspecified amount of damages. Many of the details of the lawsuit remain confidential. When the album was released in August 2001, it had a photograph of Aguilera when she was fifteen years old.

Although Aguilera's debut album was very well received, she was dissatisfied with the music and image her management had created for her. Aguilera was marketed as a bubblegum pop singer because of the genre's upward financial trend. She mentioned plans of her next album to have much more depth, both musically and lyrically. Aguilera's views of Steve Kurtz's influence in matters of the singer's creative direction, the role of being her exclusive personal manager and overscheduling had in part caused her to seek legal means of terminating their management contract.

In October 2000, Aguilera filed a Breach of fiduciary duty lawsuit against Kurtz for improper, undue and inappropriate influence over her professional activities, as well as fraud. According to legal documents, Kurtz did not protect her rights and interests. Instead, he took action that was for his own interest, at the cost of hers. The lawsuit came about when Aguilera discovered Kurtz used more of her commissionable income than he was allotted, and had paid other managers to assist him. She also petitioned the California State Labor Commission to nullify the contract. After terminating Kurtz's services, Irving Azoff was hired as her new manager.

Kurtz countersued later that month for breach of contract, claiming that the singer violated the same agreement she had sued to void. In the lawsuit, he included others close to Aguilera, alleging their intent to sabotage his business relationship with her. He also singled out Azoff for being in violation of the terms of Kurtz's contract. During this time, while she was also working on her second album, she later revealed that she was betrayed by several friends, and hit rock bottom. She used her then-upcoming album as therapy, saying "this record saved me from insanity."

On October 29, 2002, after much delay, Aguilera's second full-length English album, Stripped, was released, selling more than 330,000 copies in the first week and peaking at #2 on the Billboard 200. Unlike previous work, the album showcased Aguilera's raunchier side. The majority of Stripped was co-written by Aguilera (who had recently signed a global music publishing contract with BMG Music Publishing), and was influenced by many different subjects and music styles, including contemporary R&B, gospel, soul, balladry, pop rock, and hip hop. The majority of the album was produced by Scott Storch and singer-songwriter Linda Perry who produced her more personal records. Rockwilder and singer Alicia Keys also contributed a track each. Upon initial release, the album was very well-received by critics, although Aguilera's vocals were overlooked as she began to cultivate a more sexually provocative image. After the release of the album, she took part in photoshoots for magazines, many of these photographs featured her nude or semi-nude. Her cover for Rolling Stone, featured the singer only wearing boots and a well-placed electric guitar. It was during this time Aguilera referred to herself as "Xtina", even getting a tattoo of her nickname on the back of her neck and several piercings.

Initially, the raunchy image had a negative effect on Aguilera in the U.S., especially after the release of her controversial "Dirrty" music video. She denied that this change was a matter of publicity, claiming that the image better reflected her true personality than did the image she cultivated back in 1999. While the video for "Dirrty" became very popular on MTV, it disappointed on the U.S. singles chart. However, the single was a hit worldwide, reaching number one in the UK and Ireland. The album reached the top five on the U.K., U.S. and Canadian album charts. The second single, "Beautiful" received critical praise. The classically influenced ballad reached number one in several countries and peaked at #2 in the US. "Beautiful" earned Aguilera the Grammy for Best Female Pop Vocal Performance. Three more singles ("Fighter", "Can't Hold Us Down" featuring Lil' Kim, "The Voice Within") were released in the following two years and were hits that helped the album stay on the charts for the next two years. Stripped stayed on the U.S. and UK album charts well into 2004, and went on to be certified four-times platinum in the U.S. with over nine million copies sold worldwide. It appeared at number ten on Billboard's year-end album chart. Kelly Clarkson's second single "Miss Independent" was co-written by Aguilera, having been half-finished for Stripped.

Aguilera joined Justin Timberlake that June on the final leg of his international Justified tour, held in the U.S. This portion of the tour became a co-headliner called the "Justified & Stripped Tour". In August, an overhead lighting grid collapsed from the ceiling of the Boardwalk Hall in Atlantic City, New Jersey, causing major damage to the sound and video equipment below. Because the collapse occurred hours before the show, only a few stagehands were injured, but a few shows were cancelled or postponed. In the fourth quarter of that year, Aguilera continued to tour internationally without Timberlake, and changed the name of the tour to the "Stripped World Tour". She also dyed her hair black. It was one of the top-grossing tours of that year, and sold out most of its venues. Rolling Stone readers named it the best tour of the year. She was a special guest performer with the Pussycat Doll's dance troupe and appeared on a Maxim spread alongside them. Her second Maxim cover that year set record sales for the issue, by the end of the year she topped the annual Hot 100 list later saying, "We had fun working with certain clothes, or the lack thereof." After much delay, Aguilera's first DVD live-recording from a concert tour, Stripped Live in the UK, was released in November 2004.

In light of the tour's success, another U.S. tour was scheduled to begin in mid-2004 with a new theme. The tour however was scrapped because of the vocal cord injuries Aguilera suffered shortly before the tour's opening date. In a tribute to Madonna's performance at the inaugural MTV Video Music Awards, Aguilera performed a kiss with the singer-actress at the 2003 edition of the ceremony in August. The incident occurred during the opening performance of Madonna's songs "Like a Virgin" and "Hollywood" with fellow popstar Britney Spears.

Aguilera later decided to embrace a more mature image; this move was met with more praise than criticism, with articles using punch lines such as "From Crass to Class." She eventually dyed her hair cherry blonde and recorded a jingle, "Hello", for a Mercedes-Benz ad. Shortly after, she dyed her hair blonde and cut it short, and took on a Marilyn Monroe look; she is one of the main proponents (along with Dita Von Teese, Gwen Stefani, and Ashley Judd) in bringing back the 1920s-1940s Hollywood glamour look.

In late summer 2004, Aguilera released two singles. The first, "Car Wash", was a remake of the Rose Royce disco song recorded as a collaboration with rapper Missy Elliott for the soundtrack to the film Shark Tale. The second song was also a collaboration, but this time as a second single from one of Nelly's double-release albums, Sweat, titled "Tilt Ya Head Back". Both singles failed commercially in the U.S., but did considerably better in other parts of the world.

Aguilera collaborated with jazz artist Herbie Hancock on a cover of Leon Russell's "A Song for You" recorded for Hancock's album Possibilities, released in August 2005. Aguilera and Hancock were later nominated for the Grammy Award for Best Pop Collaboration with Vocals. She helped open the 50th Anniversary for Disneyland performing "When You Wish upon a Star", and she also collaborated with Andrea Bocelli on the song "Somos Novios" for his album Amore.

Aguilera's third English studio album, Back to Basics, released August 15, 2006, debuted at #1 in the U.S., the U.K. and eleven other countries. Aguilera described the double CD as "a throwback to the 20s, 30s, and 40s-style jazz, blues, and feel-good soul music, but with a modern twist." Although critics commented on the album's length saying, "At one disc, this would have been nothing short of masterful." The critically acclaimed lead single "Ain't No Other Man" was a substantial success, reaching #2 on the World Chart, #6 in the U.S., and #2 in U.K. Producers on the album included DJ Premier, Kwamé, Linda Perry, and Mark Ronson. One track, "F.U.S.S.", was written as a response to the animosity between Aguilera and her former producer Scott Storch. In an interview she said, "That's a way of burying my experience with him. When I tried to work with him again, he made uncalled-for demands. It was disappointing that someone would get affected like that." She received writing credit for the album and was the executive producer. The follow-up singles did very well in different regions, "Hurt" in Europe and "Candyman" in the Pacific. She co-directed both music videos, the former with Floria Sigismondi who directed her "Fighter" video, and the latter, "Candyman", with director/photographer Matthew Rolston which was inspired by The Andrews Sisters. Back to Basics has shipped 4,5 million copies worldwide.

In late 2006 Aguilera collaborated with Sean "Diddy" Combs on a track, titled "Tell Me", from his album Press Play. She also began the "Back to Basics Tour" in Europe followed by a 41-date North American tour in early 2007. After this, she toured Asia and Australia, where it was supposed to end on August 3, however she canceled her dates in Melbourne and her final two in Auckland due to an illness. Her extravagant arena tour included cabaret, three-ring circus and juke joint sets and 10 piece costumes designed by Roberto Cavalli. It was the most successful US tour by a female in 2007. In early 2008, she released her concert DVD Back to Basics: Live and Down Under.

At the 49th Grammy Awards, Aguilera again won the Best Female Pop Vocal Performance for "Ain't No Other Man". She made a noteworthy performance at the ceremony paying tribute to James Brown with her rendition of his song "It's a Man's Man's Man's World". In January 2007, she was named the 19th richest woman in entertainment by Forbes, with a net worth of US$60 million.

Aguilera performed "Steppin' Out With My Baby" with Tony Bennett on his NBC special Tony Bennett: An American Classic and on Saturday Night Live. They performed at the 59th Primetime Emmy Awards where both specials received Emmys. "Steppin' Out" was nominated for Best Pop Collaboration with Vocals at the 50th Annual Grammy Awards.

In 2008 Aguilera was featured on the soundtrack to the film, Shine a Light, from a live recording of the song "Live With Me" with the Rolling Stones. The film's soundtrack was released on April 1, 2008. To commemorate Aguilera's ten years in the music industry, RCA Records released, Keeps Gettin' Better - A Decade of Hits on November 11, 2008 exclusively at Target stores. The greatest hits included her first three number one singles, and other songs released from her previous three albums. The album's lead single, "Keeps Gettin' Better" was premiered at the 2008 MTV Video Music Awards and was her highest debut peaking at #7 on the Billboard Hot 100.

She described her forthcoming album as "short, sweet and completely different" from Back to Basics. In a July 2008 interview Aguilera revealed several details about her album saying, "I can tell you that this record is all about fun. I'll be referencing Pop art, Andy Warhol's art. So it will fun and fast-paced, and visually, it will be full of color". She also added, "there's also going to be a modern element to it that comes from my love of Tokyo". Australian singer-songwriter Sia, will contribute her songwriting skills for Aguilera's album saying, "I'm going to write with Christina in mid-September - It might not work, she might not like any of the stuff I write, and it may not make the cut, but I'm pretty excited about it." "I'm definitely a fan of Sia's, "I was thrilled she also wanted to work together and, in turn, was a fan of mine." Aguilera will also be working with Goldfrapp and Ladytron. The album is expected for release during summer 2009 and will be mostly produced by long time collaborator Linda Perry.