Utada was born in Manhattan as the only child of Teruzane, a Japanese record Producer, and his wife Junko, an enka singer, performing under the stage name Keiko Fuji. At the age of 10, Utada began to write music and lyrics. She did her recordings with her mother, releasing songs under a band named "U3" (also known as Utada 3) until 1996 when she started her first solo project, "I'll be Stronger."  The "Cookin' With Moses Vocal" from this project was called the "Cookin' With Gas Vocal" on the promotional release.

"I'll Be Stronger" was released under the Artist name Cubic U, a mathematical reference to her being the third Utada "power", and was Hikaru's pseudonym before becoming a superstar in Japan. The song was not released in the United States, and in 1997, she started her next project, though at first she was hesitant. Cubic U released her debut single "Close to You", which was a cover of The Carpenters' song. She then released her debut album Precious the following year. Both the album and single failed to chart on the Oricon charts.

Utada moved to Tokyo in the summer of 1998 and attended Seisen International School, and later the American School in Japan, while continuing to record on a new contract with Toshiba-EMI. Her movement originally came from Japanese FM radio. She opted for becoming a singer-songwriter instead of attempting to become an idol. Leading up to the release of her Japanese debut album First Love, aged 16, Utada released two successful million-selling singles: "Automatic/Time Will Tell" and "Movin' On Without You". "Automatic/Time Will Tell" sold over two million copies. Backed by her singles, her debut album First Love went on to sell over 7 million units in Japan alone (with an additional 3 million overseas, bringing it to a sum of at least 10 million units), becoming the highest selling album in Japan's recent history. The album yielded the single "First Love", which peaked at the number-two spot. By the end of the year, Utada was rank number 5 on a Japanese radio station Tokio Hot 100 Airplay's Top 100 Artists of the 20th Century by the station and its listeners.

Her song "Prisoner of Love" was used as the theme-song for the television drama Last Friends. Although "Prisoner of Love" was not initially released as a single alone, it reached number 1 in iTunes and the Chako-Uta charts after it was released as a single for the drama. It reached number 2 at the Oricon Weekly charts. It won Best Theme Song at the 57th Drama Academy Awards and sold 2.9 million downloads. It marked the fourth successful Utada drama tie-in (following 1999's Majo no Jōken and First Love, 2001's Hero and Can You Keep a Secret and 2007's Hana Yori Dango and Flavor of Life).

By the end of the 2000s, Utada was deemed "the most influential Artist of the decade" in the Japanese music landscape by The Japan Times. Utada's commercial success has made her one of Japan's top-selling recording artists of all time with over fifty-two million records sold since launching her career in the late 1990s. Twelve of her singles have reached number-one on the Oricon Singles Chart, while nine of her albums have become chart-toppers. Six of her full-length releases are among the country's highest-selling albums of all time; including First Love, Distance and Deep River, which are among the top ten best-selling records of Japan's music history. Additionally, Utada is best known by international audiences for writing and producing two theme-song contributions to Square Enix and Disney's collaborative video game series Kingdom Hearts: "Simple and Clean" and "Sanctuary".

In 2001, Utada recorded a song for the action-comedy film Rush Hour 2, Blow My Whistle, which is a collaboration with American Rapper Foxy Brown, and was written by Utada herself, alongside Pharrell Williams and Chad Hugo. The song is included on Def Jam's Rush Hour 2 Soundtrack, which peaked the 11th spot on both the Billboard 200 and the Top R&B/Hip-Hop Albums and also the 1st on the Top Soundtracks. Although Utada usually produces her own songs, Blow My Whistle was produced by The Neptunes.

On September 7, 2002, Utada married Kazuaki Kiriya, a Photographer and film Director who had directed several of her music videos. He was fifteen years her senior. On March 2, 2007, the couple announced their divorce, citing personal changes and lack of communication due to the nature of their jobs. In September 2009, Utada dated an anonymous man who was 8 years her senior. On January 27, 2010, it was reported that they had ended their relationship.

In 2003, Utada's promotional and personal life schedules became more active due to her marriage and an imposing agreement with Island Records in the United States to release a "proper" full-English debut album. Though she released "Colors", it was her only single release for 2003. The song featured experimental tones for the first time in Utada's discography. It became her longest charting single ever with a 45-week trajectory on the Oricon Singles chart, selling 881,000 copies, and was number 3 on the Yearly Singles chart.

In mid-2004, Utada moved back to New York, and began work on a new recording contract with Island Def Jam Music Group. On October 5, 2004, she released her North American English-language debut album, Exodus, under the name "Utada," which was her new American-given Artist title at the Universal Convention. It was released on September 9 in Japan, with a special booklet and housed in a cardboard slipcase. In an MTV interview, Utada said: "I don't think it's the music that I'm concerned about. It's obviously that I look really different and there really aren't any completely Asian people [who are popular Singers in the U.S.] right now." Exodus became Utada's fourth consecutive release to debut at number 1 and boast 500,000 copies in its first-week sales in Japan. American sales were not as successful, it reached number 160 in the US Billboard 200 chart; it however peaked at number 5 in the Heatseekers chart. "Easy Breezy" was released as the lead single in early August 2004, followed up by "Devil Inside" a month and two weeks later. And Utada became the cover of the Interview magazine June 2005 issue.

The fourth single from Exodus, "You Make Me Want to Be a Man", was released in October 2005 in the UK. "Devil Inside" became a club hit in the U.S. and topped the Billboard Hot Dance/Club Airplay charts. Both the Exodus album and the "You Make Me Want to Be a Man" single were released in the UK, with different artwork from the USA and Japanese versions.

An announcement was made that Utada would perform a short concert tour titled Wild Life at Yokohama Arena, Yokohama to promote the album, her first Japanese concert since 2006's Utada United.

The year 2007 ended with the single "Flavor of Life" becoming the best seller of 2007 and with Utada being voted "Number 1 Favorite Artist of 2007" by Oricon's annual readers poll, three years after she was last voted number 1 on the poll. She sold 12 million digital ringtones and songs in 2007, the highest of a Japanese Artist in one year. The single was featured as the main song in second season of TV drama Hana Yori Dango.

On December 16, 2008, information leaked onto the Internet that Utada's next English-language single, titled "Come Back to Me", would be scheduled for airplay release through U.S. Rhythmic/Crossover and Mainstream formats on February 9 and 10, 2009 respectively via Island Records. The new English album, titled This Is the One, was released on March 14, 2009 in Japan and on May 12, 2009 in the United States. This Is the One debuted at number 1 in Japan on March 13, 2009, the day it was released in Japan, but became Utada's first album not to top the weekly chart since Precious. On March 30, 2009 she appeared on New York City radio station Z-100 (100.3), the largest pop radio program in the U.S., and granted a live on-air interview on the station's Elvis Duran Morning Show, a breakthrough that would lead to a promotional schedule up and through the album's international physical release on May 12. Utada also sang the theme song for the second Evangelion film, Evangelion: 2.0 You Can (Not) Advance. The single was released on June 27, 2009, and is a remix of her previous single, "Beautiful World". The new single is titled Beautiful World -PLANiTb Acoustica Mix-.

On December 21, 2009, Utada's Dirty Desire remixes were released only on Amazon.com, Zune Marketplace, and the U.S. iTunes Store, in support of This Is the One and her upcoming tour. The tour, Utada: In the Flesh 2010, was her first concert tour outside Japan and included eight cities in the US and two dates in London, UK. The tickets for the second London performance went on public sale November 13, and reportedly sold out in just 5 hours.

Utada held a short, two-concert tour before her hiatus began, titled Wild Life, on December 8 and 9, 2010, performing both dates at Yokohama Arena, Yokohama. The December 8 concert was broadcast in 64 cinemas in Japan; while it was simultaneously broadcast on Ustream, a live video streaming website. Between the two channels set up for the concert on Ustream, they were accessed a total of 925,000 times, with 345,000 unique viewers, which was a global record on Ustream.tv for the highest number of simultaneous accesses of any video, with the previous highest being only 100,000.

On December 7, 2011, Recochoku updated their yearly download and awards chart, with Utada's Utada Hikaru Single Collection Vol. 1 being the second most downloaded album of 2011.

On November 16, 2012, Utada's YouTube account uploaded a video entitled "桜流し" ("Sakura Nagashi", meaning "Flowing Cherry Blossoms"). The song featured is Utada's newest single. The single was co-written with Paul Carter, and was digitally released on November 17, 2012. A DVD single was released a month later. "Sakura Nagashi" is the theme song from the animation movie Evangelion: 3.0 You Can (Not) Redo.

On August 22, 2013, Utada's mother, Keiko Fuji, died by apparent suicide by jumping from the thirteenth floor of a 28-floor condominium building in Shinjuku, Tokyo.

On February 3, 2014, through an announcement on her personal site, Utada said that she was engaged to be wed, asking for her fans and the media to view her personal life from a "respectable distance" as he is not in the entertainment industry. On the same day, her ex-husband Kazuaki Kiriya congratulated her on the new marriage. On February 10, 2014, Utada and her fiancé Francesco Calianno left a message at the official site of Utada explaining how they met each other, his being a bartender in a London hotel, and asking for privacy. They were wed on May 23, 2014.

On July 3, 2015, Utada announced that she had given birth to a son.

On 8 August 2016, the album's title, track list and cover were released. The album's title was announced as Fantôme (French: ghost), containing 8 new songs, as well as the previous 3 singles, for a track listing totalling 11 tracks. The new album marked a first for Utada to be released in an SHM-CD format. Following its release on September 28, Fantôme was commercially and critically successful. It debuted atop the Oricon Albums Chart and stayed there for four consecutive weeks, the most of any of her studio albums since First Love. It was awarded Album of the Year at the Japan Record Awards and received positive reviews from media outlets. At the end of the year, it was ranked the third-best-selling physical record of the year by Oricon, as well as the best-selling digital album, according to Billboard Japan.

On February 9, 2017, it was announced that Utada is switching labels to Sony Music Japan sublabel Epic Records once her contract with Universal expires in March. The label announced that new material will be released later in 2017. The first digital single under the label, called "Oozora de Dakishimete", was released digitally worldwide on July 10, 2017. The second one, called "Forevermore", was released on July 28. It features the Drummer Chris Dave. A third digital single, called "Anata", was released on December 8. The song was chosen as the theme for the movie Destiny: Kamakura Monogatari.

On April 6, 2018, Utada divorced Francesco Calianno.