"Girlfriend" was released as the lead single from her third studio album, The Best Damn Thing (2007) on February 27, 2007 by Columbia and RCA Records.

The song's accompanying music video, directed by The Malloys, sees Lavigne portraying three alter-egos, with all of them fighting over the same guy.

Following the release of her second studio album, Under My Skin (2004), Lavigne wanted to record more "fun and upbeat" music.

[4] Lavigne was initially hesitant to release "Girlfriend" as the lead single from The Best Damn Thing, referring to the song's conception as "just a joke.

"[5] The song was not based on a personal experience, with Lavigne opting to write about general topics to appeal to a wider audience.

[6] In an effort to appeal to non-English markets, Lavigne recorded the song's chorus in seven different languages, including Spanish, French, Italian, Portuguese, German, Japanese, and Mandarin.

[14] On July 2, 2007, the Rubinoos frontman Tommy Dunbar and songwriter James Gangwer filed a lawsuit for infringement of copyright against Lavigne, Dr. Luke, RCA Records, and Apple.

[17] Lavigne's manager, Terry McBride, similarly refuted the allegations, referring to Dunbar and Gangwer's claims as baseless.

[17] While McBride contended that the songs were dissimilar, he acknowledged that Lavigne would be willing to settle the case to avoid expensive legal proceedings.

[18] In January 2008, Dunbar and Gangwer's attorney, Nicholas Carlin, confirmed that a confidential settlement had been reached between the two parties, but refused to comment further.

[19] However, Dunbar and Gangwer later released a joint statement on January 15, 2008 in which they claimed to "completely exonerate" Lavigne and Dr. Luke from any wrongdoing.

"[21] Christian Hoard of Rolling Stone called it a "hypercatchy, giant-sounding 'Hey Mickey' tribute", and commented that the song is one of the album's "monster pleasures".

[22] Chris Willman of Entertainment Weekly noted the popularity of the song, referring to Lavigne as an "alpha female out to steal a stud from a meek rival who’s 'like, so whatever'".

[23] Stephen Thomas Erlewine of AllMusic highlighted the song as a 'track pick' in a review of the album, The Best Damn Thing.

[24] Jon Pareles of The New York Times also highlighted "Girlfriend" as the best song off of The Best Damn Thing, commenting that it used "cleverly manipulated echoes and attacks to sound as if Ms. Lavigne were charging in from all directions".

[25] Jody Rosen of Slate referred to "Girlfriend" as "brash and catchy", praising the song's "shout-along vocals, power chords, [and] hand claps amplified to sound like an army on the march".

[27] Laura Snapes of The Guardian also compared "Girlfriend" to "Mickey", referring to the song as a "deadpan cheerleader banger".

[30] MuchMusic attributed the success of the song to the mix of various genres, stating: "[Lavigne] can succeed in punk, rock and pop with her bubblegum anthem 'Girlfriend'".

Because of digital download sales in excess of 122,000, the song debuted at number five on the US Billboard Hot 100 chart, becoming her fifth and last top ten hit.

Thus, the song has sold more than 3,000,000 copies there making it the best-selling single by a western female artist of all time on Japan.

[45][46] In July, Lavigne's manager Terry McBride claimed that the singer was owed $2 million in revenue from YouTube.

[51] The song is featured on the soundtrack to the video game Burnout Dominator in four different languages which includes Japanese, Spanish, Mandarin and English.

Lavigne performed "Girlfriend" at the Orange Lounge in Toronto on August 23, 2007,[84] for the AOL Sessions on May 24, 2011,[85] and more recently with Travis Barker for SiriusXM + Pandora's Small Stage Series concert in February 2022.