YG Entertainment released the song for digital download and streaming as the third single from the group's self-titled second extended play (EP) on June 24, 2011.

Written and produced by Teddy Park, "I Am the Best" is an electro house and electropop track that integrates hip hop and Middle Eastern elements through its instrumentation.

Music journalists praised the production and 2NE1's performance and considered it a pioneer of the Korean wave and K-pop's "girl crush" concept, which denotes themes of ferocity and female empowerment.

The song received renewed attention after appearing in a 2014 commercial for Microsoft's Surface Pro 3; Capitol Records released it in the United States on December 10, 2014.

[4] In a press release, YG announced that it was an "intense" song combining electronic music and hip hop, which appealed to youths who were part of the clubbing culture.

[6] The Japanese-language version of the song was first made available for download via Recochoku [ja] on July 20, 2011, and was later included in the Japanese edition of the EP (Nolza) on September 21 as part of the group's debut in the country.

[7] Prior to the release of CL's first studio album Alpha in 2021, she held a live countdown event and played several snippets of unreleased versions of songs from both herself and 2NE1, and revealed that "I Am the Best" had originally featured Canadian singer Justin Bieber.

Discussing the rise of the Korean wave in November 2011, James Brooks of Pitchfork highlighted the song's "show-stopping" energy and 2NE1's "manic, larger-than-life charisma".

[18] In The New York Times, Jon Caramanica wrote that the song was "a postcard from the moment" when K-pop, which had been bound by the sound of other countries, "was beginning to embrace excess as its own style".

[19] Slant Magazine featured it in their list of the 25 Best Singles of 2011; critic Jonathan Keefe described the track as "a jaw-dropping, vibrant triumph of pure swagger and verve" and cited it as an example of the "unmitigated joy of K-pop".

[20] Korean Music Awards selection committee member Seo Jeong-min highlighted the song's "powerful, sensuous, and addictive electronic sound", and asserted that it firmly establishes itself as one of the representative tracks of K-pop.

[21] In Spin's June 2012 list of the 21 Greatest K-Pop Songs of All Time, "I Am the Best" ranked at number three, with Chuck Eddy writing that it "might've been the best single released on the planet in 2011".

[22] In October 2013, the Smithsonian Institution recognized "I Am the Best" as a key work in the spread of the Korean wave around the world with "Gangnam Style" by Psy, and "Fantastic Baby" by Big Bang, among others.

[41] By the end of 2011, the song had accumulated a total of 3.47 million units in digital sales, and ranked as the fourth best-selling single of the year in South Korea.

[60] The visual incorporates glam punk fashion and street style ensembles designed by Sophie Hulme, Gemma Slack, Cassette Playa and Gareth Pugh.

[31] In Billboard's article "Top 5 Must-See Music Videos From the K-Pop Phenoms" marking the group's fifth anniversary, Jeff Benjamin commented that "throughout all the looks, styles and sound, none seem to define 2NE1 as much as 'I Am the Best.

[79] After the release of the choreography practice video, the group announced a dance contest for the song on July 8, where 2NE1 and their choreographers would choose the four best submissions to win exclusive concert tickets for their upcoming Nolza tour in Seoul, Adidas Originals merchandise, and 2NE1 stage attire.

[82] The group performed "Lonely" and "I Am the Best" at the 2011 Mnet Asian Music Awards in Singapore on November 29, 2011, where they sported black outfits with gold and silver ornaments.

[84] The following month, they reprised the song at the MTV Iggy Best New Band in the World Concert at Times Square's Best Buy Theater[85] and at the 2011 SBS Gayo Daejeon.

Writing for Billboard, Caitlin Kelley defined "girl crush" as "anything that conveys the image of ferocity, stepping outside the expectations of hyperfemininity", but also amounting to "more abstract ideas of relatability, aspiration and female empowerment."

[113] Regarding the song's international exposure, Jeff Benjamin of Billboard wrote that "K-pop has much of its overseas travel to thank for this absolute monster of a pop smash.

In 2021, Billboard editor Nolan Feeney wrote that "I Am the Best" "lives up to its name a decade later", and considered it to have helped pave the way for K-pop's takeover in America.

He added that the 10-second opening sung by CL "will be remembered as a critical moment in K-pop history", along with the intro to "Gangnam Style" released the following year.

[28] Rolling Stone ranked it the eighth greatest song in the history of Korean pop music in 2023, stating that "2NE1 established a new industry standard".