Mariah Carey was born in Huntington, Long Island, New York. She is the third and youngest child of Patricia (née Hickey), a former opera singer and vocal coach of Irish descent, and Alfred Roy Carey, an aeronautical engineer of Afro-Venezuelan descent. Carey's parents divorced when she was three years old. While living in Huntington, racist neighbors allegedly poisoned the family dog and set fire to her family's car. After her parents' divorce, Carey had little contact with her father, and her mother worked several jobs to support the family. She spent much of her time at home alone, and turned to music to occupy herself. She began singing at around the age of three, when her mother began to teach her after Carey imitated her mother practicing Verdi's opera Rigoletto in Italian.

She graduated from Harborfields High School in Greenlawn, New York. She was frequently absent due to her work as a demo singer for local recording studios; her classmates consequently gave her the nickname "Mirage". Her work in the Long Island music scene gave her opportunities to work with musicians such as Gavin Christopher and Ben Margulies, with whom she co-wrote material for her demo tape. After moving to New York City, Carey worked part-time jobs to pay the rent and completed five hundred hours of beauty school. Eventually, she became a backup singer for Puerto Rican freestyle singer Brenda K. Starr.

In 1988, Carey met Columbia Records executive Tommy Mottola at a party, where Starr gave him Carey's demo tape. Mottola played the tape when leaving the party and was impressed. He returned to find Carey, but she had left. Nevertheless, Mottola tracked her down and signed her to a recording contract. This Cinderella-like story became part of the standard publicity surrounding Carey's entrance into the industry.

Carey co-wrote the tracks on her 1990 debut album Mariah Carey, and she has continued to co-write the majority of her material since. During the recording, she expressed dissatisfaction with the contributions of producers such as Ric Wake and Rhett Lawrence, whom the executives at Columbia had enlisted to help make the album more commercially viable. Backed by a substantial promotional budget, the album reached number one on the U.S. Billboard 200 chart, where it remained for several weeks. It yielded four number-one singles, and made Carey a star in the United States, but was less successful in other countries. Critics rated the album highly, and Carey won Grammys for Best New Artist, and—for her debut single, "Vision of Love"—Best Female Pop Vocal Performance.
Carey conceived Emotions, her second album, as a homage to Motown soul music (see Motown Sound), and she worked with Walter Afanasieff and Clivillés & Cole (from the dance group C&C Music Factory) on the record. It was released soon after her debut album—in late 1991—but was neither critically nor commercially as successful; Rolling Stone described it as "more of the same, with less interesting material pop-psych love songs played with airless, intimidating expertise". The title track "Emotions" made Carey the only recording act to have their first five singles reach number one on the U.S. Hot 100 chart, though the album's follow-up singles failed to match this feat. Carey had been lobbying to produce her own songs, and beginning with Emotions, she has co-produced most of her material. "I didn't want to be somebody else's vision of me", she said. "There's more of me on this album".

Although Carey performed live occasionally, stage fright prevented her from embarking on a major tour. Her first widely seen appearance was featured on the television show MTV Unplugged in 1992, and she remarked that she felt her performance that night proved her vocal abilities were not, as some had previously speculated, simulated with studio equipment. Alongside acoustic versions of some of her earlier songs, Carey premiered a cover of The Jackson 5's "I'll Be There" with her back-up singer Trey Lorenz. The duet was released as a single, reached number one in the U.S., and led to a record deal for Lorenz, whose debut album Carey later co-produced. Because of high ratings for the Unplugged television special, the concert's set list was released on the EP MTV Unplugged, which Entertainment Weekly called "the strongest, most genuinely musical record she has ever made Did this live performance help her take her first steps toward growing up?".

Carey and Tommy Mottola had become involved romantically during the making of her debut album, and in June 1993, they were married.
Kenneth "Babyface" Edmonds consulted on the album Music Box, which was released later that year and became Carey's most successful worldwide. It yielded her first UK Singles Chart number-one, a cover of Badfinger's "Without You", and the U.S. number-ones "Dreamlover" and "Hero". Billboard magazine proclaimed it "heart-piercing easily the most elemental of Carey's releases, her vocal eurythmics in natural sync with the songs", but TIME magazine lamented Carey's attempt at a mellower work, " seems perfunctory and almost passionless Carey could be a pop-soul great; instead she has once again settled for Salieri-like mediocrity." In response to such comments, Carey said, "As soon as you have a big success, a lot of people don't like that. There's nothing I can do about it. All I can do is make music I believe in." Most critics slighted the opening of her subsequent U.S. Music Box Tour.
In late 1994, after her duet with Luther Vandross on a cover of Lionel Richie and Diana Ross's "Endless Love" became a hit, Carey released the holiday album Merry Christmas. It contained cover material and original compositions such as "All I Want for Christmas Is You", which became Carey's biggest single in Japan, and, in subsequent years, emerged as one of her most perennially popular songs on U.S. radio. Critical reception of Merry Christmas was mixed, with Allmusic calling it an "otherwise vanilla set pretensions to high opera on 'O Holy Night' and a horrid danceclub take on 'Joy to the World'". It became the most successful Christmas album of all time.

In 1995, Columbia released Carey's fifth album, Daydream, which combined the pop sensibilities of Music Box with downbeat R&B and hip hop influences. A remix of "Fantasy", its first single, featured rapper Ol' Dirty Bastard. Carey said that Columbia reacted negatively to her intentions for the album: "Everybody was like 'What, are you crazy?'. They're very nervous about breaking the formula." It became her biggest-selling album in the U.S., and its singles achieved similar success — "Fantasy" became the second single to debut at number one in the U.S. and topped the Canadian Singles Chart for twelve weeks, "One Sweet Day" (a duet with Boyz II Men) spent a record-holding sixteen weeks at number one in the U.S., and "Always Be My Baby" (co-produced by Jermaine Dupri) was the most successful on U.S. radio in 1996, according to Billboard magazine. Daydream generated career-best reviews for Carey, and publications such as The New York Times named it one of 1995's best albums; the Times wrote that its "best cuts bring pop candy-making to a new peak of textural refinement Carey's songwriting has taken a leap forward, becoming more relaxed, sexier and less reliant on thudding clichés". The short but profitable Daydream World Tour augmented sales of the album, which received six Grammy Award nominations.

Carey and Mottola officially separated in 1997. Although the public image of the marriage was a happy one, she said that in reality she had felt trapped by her relationship with Mottola, whom she often described as controlling. They officially announced their separation in 1997, and their divorce became final the following year. Soon after the separation, Carey hired an independent publicist and a new attorney and manager. She continued to write and produce for other artists during this period, contributing to the debut albums of Allure and 7 Mile through her short-lived imprint Crave Records.

Carey's next album, Butterfly (1997), yielded the number-one single "Honey", the lyrics and music video for which presented a more overtly sexual image of her than had been previously seen. She stated that Butterfly marked the point that she attained full creative control over her music. However, she added: "I don't think it's that much of a departure from what I've done in the past It's not like I went psycho and thought I was going to be a rapper. Personally, this album is about doing whatever the hell I wanted to do." Reviews were generally positive: LAUNCHcast said Butterfly "pushes the envelope", a move its critic thought "may prove disconcerting to more conservative fans" but praised as "a welcome change". The Los Angeles Times wrote, " is easily the most personal, confessional-sounding record she's ever done Carey-bashing just might become a thing of the past." The album was a commercial success—though not to the degree of her previous three albums—and "My All" (her thirteenth Hot 100 number-one) gave her the record for the most U.S. number-ones by a female artist.

Towards the turn of the millennium, Carey was developing the film project Glitter, and wrote songs for the films Men in Black (1997), and How the Grinch Stole Christmas (2000). During the production of Butterfly, Carey became romantically involved with New York Yankees baseball star Derek Jeter. Their relationship ended in 1998, with both parties citing media interference as the main reason for the split. The same year, Columbia released the album #1's, a collection of Carey's U.S. number-one singles alongside new material, which she said was a way of rewarding her fans. The song "When You Believe", a duet with Whitney Houston, was recorded for the soundtrack of The Prince of Egypt (1998) and won an Academy Award. #1's sold above expectations, but a review in NME labeled Carey "a purveyor of saccharine bilge like 'Hero', whose message seems wholesome enough: that if you vacate your mind of all intelligent thought, flutter your eyelashes and wish hard, sweet babies and honey will follow". Also that year, she appeared on the first televised VH1 Divas benefit concert program, though her alleged prima donna behavior had already led many to consider her a diva. By the following year, she had entered a relationship with singer Luis Miguel.

Rainbow, Carey's seventh studio album, was released in 1999 and comprised more R&B/hip hop-oriented songs, many of them co-created with Jimmy Jam and Terry Lewis. "Heartbreaker" and "Thank God I Found You" (the former featuring Jay-Z, the latter featuring Joe and boy band 98 Degrees) reached number one in the U.S., and the success of the former made Carey the only act to have a number-one single in each year of the 1990s. A cover of Phil Collins's "Against All Odds (Take a Look at Me Now)" went to number one in the UK after Carey re-recorded it with boy band Westlife. Media reception of Rainbow was generally enthusiastic, with the Sunday Herald saying the album "sees her impressively tottering between soul ballads and collaborations with R&B heavyweights like Snoop Doggy Dogg, Usher It's a polished collection of pop-soul". VIBE magazine expressed similar sentiments, writing, "She pulls out all stops Rainbow will garner even more adoration", but it became Carey's lowest selling album up to that point, and there was a recurring criticism that the tracks were too alike. When the double A-side "Crybaby" (featuring Snoop Dogg)/"Can't Take That Away (Mariah's Theme)" became her first single to peak outside the U.S. top twenty, Carey accused Sony of under promoting it: "The political situation in my professional career is not positive I'm getting a lot of negative feedback from certain corporate people", she wrote on her official website.

After receiving Billboard's Artist of the Decade Award and the World Music Award for Best-Selling Female Artist of the Millennium, Carey parted from Columbia and signed a contract with EMI's Virgin Records worth a reported US$80 million. She often stated that Columbia had regarded her as a commodity, with her separation from Mottola exacerbating her relations with label executives. Just a few months later, in July 2001, it was widely reported that Carey had suffered a physical and emotional breakdown. She had left messages on her website complaining of being overworked, and her relationship with Luis Miguel was ending. In an interview the following year, she said, "I was with people who didn't really know me, and I had no personal assistant. I'd be doing interviews all day long, getting two hours of sleep a night, if that." During an appearance on MTV's Total Request Live, Carey handed out popsicles to the audience and began what was later described as a "strip tease". By the month's end, she had checked into a hospital, and her publicist announced that Carey was taking a break from public appearances.

Critics panned Glitter, Carey's much delayed semi-autobiographical film, and it was a box office failure. The accompanying soundtrack album, Glitter, was inspired by the music of the 1980s and featured collaborations with Rick James and Jimmy Jam and Terry Lewis; it generated Carey's worst showing on the U.S. chart. The St. Louis Post-Dispatch dismissed it as "an absolute mess that'll go down as an annoying blemish on a career that, while not always critically heralded, was at least nearly consistently successful", while Blender magazine opined, "After years of trading her signature flourishes for a radio-ready purr, 's left with almost no presence at all." The lead single, "Loverboy" (featuring Cameo), reached number two on the Hot 100 thanks to a price cut, but the album's follow-up singles failed to chart.

Columbia released the low-charting compilation album Greatest Hits shortly after the failure of Glitter, and in early 2002, Virgin bought out Carey's contract for $28 million, creating further negative publicity. Carey later said her time at Virgin was "a complete and total stress-fest I made a total snap decision which was based on money, and I never make decisions based on money. I learned a big lesson from that." Later that year, she signed a $20 million contract with Island Records, and launched the record label MonarC. To add further to Carey's emotional burdens, her father, with whom she had little contact since childhood, died of cancer that year.

Following a well-received supporting role in the 2002 film WiseGirls, Carey released the album Charmbracelet, which she said marked "a new lease on life" for her. Sales of Charmbracelet were moderate, and the quality of Carey's vocals came under severe criticism. The Boston Globe declared the album "the worst of her career, revealing a voice no longer capable of either gravity-defying gymnastics or soft coos", and Rolling Stone commented, "Carey needs bold songs that help her use the power and range for which she is famous. Charmbracelet is like a stream of watercolors that bleed into a puddle of brown." The album's only charting single in America, "Through the Rain", was a failure on pop radio, which had become less open to maturing "diva" stylists such as Celine Dion, or Carey herself in favor of younger singers such as Kelly Clarkson or Christina Aguilera, who had vocal styles very similar to Carey's.

"I Know What You Want", a 2003 Busta Rhymes single on which Carey guest starred, fared considerably better and reached the U.S. top five. Columbia later included it on the remix collection The Remixes, Carey's first album not to receive an RIAA sales certification. That year, she embarked on the Charmbracelet World Tour and was awarded the Chopard Diamond award for selling over 100 million albums worldwide. She was featured on rapper Jadakiss's 2004 single "U Make Me Wanna", which reached the top ten on Billboard's R&B/Hip-Hop chart.

Carey's tenth studio album, The Emancipation of Mimi (2005), contained contributions from producers such as The Neptunes, Kanye West and Carey's longtime collaborator, Jermaine Dupri. Carey said it was "very much like a party record the process of putting on makeup and getting ready to go out I wanted to make a record that was reflective of that."; The Emancipation of Mimi became 2005's best-selling album in the U.S., and The Guardian reviewer defined it as "cool, focused and urban the first Mariah Carey tunes in years I wouldn't have to be paid to listen to again". The album earned Carey a Grammy Award for Best Contemporary R&B Album, and the single "We Belong Together" won Best Female R&B Vocal Performance and Best R&B Song. "We Belong Together" held the Hot 100's number-one position for fourteen weeks, her longest run at the top as a solo lead artist. Subsequently, the single "Shake It Off" reached number two for a week, making Carey one of fewer than a dozen music acts to have simultaneously held the Hot 100's top two positions, and the first female to do so with two lead vocals. (While topping the charts in 2002, Ashanti was the "featured" singer on the #2 single.)

Carey began a concert tour in mid-2006, called The Adventures of Mimi Tour, which was the most successful tour of her career, although some dates had to be canceled. In separate appearances on 106 & Park and TRL Carey announced plans to go back on tour in November or December of 2008. She appeared on the cover of the March 2007 edition of Playboy magazine on a non-nude photo session. In early 2007, she was featured with Bow Wow on the Bone Thugs-n-Harmony single "Lil' L.O.V.E.". Later in the year, Carey received a "recording star" on the Hollywood Walk of Fame.

By spring 2007, she had begun working on her eleventh studio album, E=MC². Asked about the album title and its meaning, Carey said "Einstein’s theory? Physics? Me? Hello! Of course I’m poking fun." She characterized the project as "Emancipation of Mimi to the second power", saying she was "freer on this album than" any other. Like her previous one, this album mainly concentrates on pop and R&B, but also borrows hip hop, gospel and even reggae ("Cruise Control") elements. Although E=MC² was well received by most critics, some of them criticized it for being "a clone of The Emancipation of Mimi". Bleu Magazine's critic said that the "facsimiles aren't terrible, they're just boring and forgettable at this point".

Two weeks before the album's release, on April 2, 2008, "Touch My Body", her first single from the album, became Carey's eighteenth number-one single on the Hot 100, pushing her past Elvis Presley into second place for the most number-one singles among all artists in the rock era, according to Billboard magazine's revised methodology (however, their statistician Joel Whitburn still credits Presley with an eighteenth). Carey is now second only to The Beatles who have twenty number-one singles.

Carey's singles have, collectively, topped the charts for seventy-nine weeks, which places her just behind Presley, who topped the combined charts for eighty weeks. Carey has also had notable success on international charts, though not to the same degree as in the United States. Thus far, she has had two number-one singles in Britain, two in Australia, and six in Canada. Her highest-charting single in Japan peaked at number two.

On April 30, 2008, Carey married actor Nick Cannon, at Carey's private estate on Windermere Island in the Bahamas. Confirming rumors of the marriage, Carey stated that she felt the pair were "soulmates". Carey was inducted into the Long Island Music Hall of Fame on October 30, 2008 at the Garden City Hotel in Garden City, New York.