For his 14th birthday, Cobain's uncle gave him the option of a guitar or a bicycle as a gift — Cobain chose the guitar. He started by learning a few covers, including "Louie Louie" and The Cars' "My Best Friend's Girl", and soon began working on his own songs.During high school, Cobain rarely found anyone with whom he could play music. While hanging out at the Melvins' practice space, he met Krist Novoselic, a fellow devotee of punk rock. Novoselic's mother owned a hair salon. Cobain and Novoselic would occasionally practice in the upstairs room of the salon. A few years later, Cobain tried to convince Novoselic to form a band with him by lending him a copy of a home demo recorded by Cobain's earlier band, Fecal Matter. After months of asking, Novoselic finally agreed to join Cobain, forming the beginnings of Nirvana.
Cobain was disenchanted after early touring, due to the band's inability to draw substantial crowds and the apparent difficulty in sustaining themselves. During their first few years playing together, Novoselic and Cobain were hosts to a rotating list of drummers. Eventually, the band settled on Chad Channing, with whom Nirvana recorded the album Bleach, released on Sub Pop Records in 1989. Cobain, however, became dissatisfied with Channing's style, leading the band to find a new drummer, eventually settling on Dave Grohl. With Grohl, the band found their greatest success via their 1991 major-label debut, Nevermind.
With the lead single "Smells Like Teen Spirit" from Nirvana's second album Nevermind (1991), Nirvana entered the mainstream, popularizing a subgenre of alternative rock, euphemistically titled grunge. Since their debut, Nirvana, with Cobain as a songwriter, sold over 25 million albums in the United States alone, and over 50 million worldwide.
The success of Nevermind provided numerous Seattle bands such as Alice in Chains, Pearl Jam, and Soundgarden wider audiences, and as a result, alternative rock became a dominant genre on radio and music television in the United States during the early-to-middle 1990s. Nirvana was considered the "flagship band of Generation X", and frontman Cobain found himself reluctantly anointed by the media as the generation's "spokesman." Cobain's discomfort with the media attention prompted him to focus on the band's music and, believing their message and artistic vision to have been misinterpreted by the public, challenged the band's audience with its third studio album In Utero (1993).
Cobain struggled to reconcile the massive success of Nirvana to his underground roots. He also felt persecuted by the media, comparing himself to Frances Farmer. He began to harbour resentments for people who claimed to be fans of the band yet refused to acknowledge, or misinterpreted, the band's social and political views. A vocal opponent of sexism, racism and homophobia, he was publicly proud that Nirvana had played at a gay rights benefit supporting No-on-Nine in Oregon in 1992, in opposition to Ballot Measure Nine, a ballot measure, that if passed, would have prohibited schools in the state from acknowledging or positively accepting LGBT rights and welfare.
Cobain was a vocal supporter of the pro-choice movement, and had been involved in Rock for Choice from the campaign inception by L7. He received death threats from a small number of anti-abortion activists for doing so, with one activist threatening Cobain that he would be shot as soon as he stepped on stage. The liner notes from Incesticide declared "if any of you in any way hate homosexuals, people of different color, or women, please do this one favor for us-leave us the fuck alone! Don't come to our shows and don't buy our records". An article from his posthumously released Journals declares that social liberation could be made possible only through the eradication of sexism.
Courtney Love met Cobain, on 12 January 1990, in Portland's Satyricon nightclubwhen they both still led ardent underground rock bands. Love made advances, but Cobain was evasive. Early in their interactions, Cobain broke off dates and ignored Love’s advances because he wasn’t sure he wanted a relationship. Cobain noted, "I was determined to be a bachelor for a few months [...] But I knew that I liked Courtney so much right away that it was a really hard struggle to stay away from her for so many months." Courtney Love first saw Cobain perform in 1989 at a show in Portland, Oregon; they talked briefly after the show and Love developed a crush on him.
Cobain was already aware of Love through her role in the 1987 film Straight to Hell. According to journalist Everett True, the pair were formally introduced at an L7 and Butthole Surfers concert in Los Angeles in May 1991.In the weeks that followed, after learning from Dave Grohl that Cobain shared mutual interests with her, Love began pursuing Cobain. In the fall of 1991 the two were often together and bonded through drug use.
Around the time of Nirvana's 1992 performance on Saturday Night Live, Love discovered that she was pregnant with Cobain's child. On 24 February 1992, a few days after the conclusion of Nirvana's Pacific Rim tour, Cobain and Love were married on Waikiki Beach in Hawaii. Love wore a satin and lace dress once owned by the actress Frances Farmer, and Cobain wore green pajamas, because he’d been "too lazy to put on a tux". In an interview with The Guardian, Love revealed the opposition to their marriage from various people: "Kim Gordon [of Sonic Youth] sits me down and says, 'If you marry him your life is not going to happen, it will destroy your life.' But I said, 'Whatever! I love him, and I want to be with him!'... It wasn't his fault. He wasn't trying to do that."but the event created a media controversy for the couple. While Cobain and Love's romance had always been a media attraction, they found themselves hounded by tabloid reporters after the article was published, many wanting to know if Frances was addicted to drugs at birth. The Los Angeles County Department of Children's Services took the Cobains to court, claiming that the couple's drug usage made them unfit parents. Two-week-old Frances Bean Cobain was ordered by the judge to be taken from their custody and placed with Courtney's sister Jamie for several weeks, after which the couple obtained custody in an exchange agreement to submit to urine tests and regular visits from a social worker. After months of legal wrangling, the couple were eventually granted full custody of their daughter.