Lee Chanhyuk and Lee Suhyun lived with their parents in Mongolia for almost two years before they returned to South Korea to pursue a career in the music industry. The siblings, under the name Akdong Musician, became part of the Proteurment agency. Under the company, they did several stage performances and even released an original song called "Galaxy", which was later used as a soundtrack for a Samsung Galaxy S4 commercial.
In August 2012, the duo participated in the preliminary auditions of K-pop Star 2, which were held at Jamsil Arena in Seoul. They passed their audition, and in the show's first round they sang a cover of Miss A's "Breathe" and an original song titled "Don't Cross Your Legs", to praise from all three judges. Park Jin-young, founder and CEO of JYP Entertainment, praised the chemistry between the siblings and the techniques they had incorporated in their performances. Singer and representative of SM EntertainmentBoA highlighted and praised the lyrics of their original song, while Yang Hyun-suk, founder and CEO of YG Entertainment, described them as "true artists" among the people who had auditioned for the show. The duo continued to receive positive responses from the judges, until after their second performance in the third round. The judges pointed out that their lack of confidence was the main reason behind their lukewarm performances in the succeeding rounds. In spite of this, they eventually won the competition.
Some of their original songs performed during the competition were released under LOEN Entertainment and were well received; "You are Attractive", released on 12 December, immediately reached the number one spot on the Gaon Charts. After the competition, despite not being signed under an entertainment agency, they participated in commercials and composed several songs. One of these songs was "I Love You" for the television seriesAll About My Romance.
On 24 May 2013, a month after winning K-pop Star 2, the siblings signed an exclusive contract with YG Entertainment.
On 7 January, SBS Variety Department's Nam Seung Yong announced that Akdong Musician would make their long awaited debut on 7 April, nine months after winning K-pop Star 2. Their debut stage would be on K-pop Star 3 on 6 April, and their first full length album would be released on 7 April.
On 2 April, YG Entertainment released the tracklist for the debut album, Play. The album has eleven songs, all written and produced by Lee Chanhyuk. Through a post on YG-Life, it was announced that Akdong Musician would have a total of three title tracks accompanied by three different music videos, with the third title song determined by fan voting. The first song, "200%", was chosen by Yang Hyun-suk, and the second song, "Melted", was chosen by Akdong Musician.
Play was released digitally on 7 April, and physically on 9 April. The album debuted at number two on Billboard's U.S. World Albums Chart.
The music video for "200%" was released on 7 April along with the digital album. Shortly after its release, "200%", topped the music charts, with the rest of the songs on the album also charting high. The music video for "Melted" was released on 14 April. The last and third title song was "Give Love", which was the third high-charting song, after "200%" and "Melted". The music video for "Give Love" was released on 2 May 2014.
On 16 June, Akdong Musician participated in YG Family's cover project, releasing a cover of Taeyang's "Eyes, Nose, Lips."
On 9 October, YG Entertainment announced that Akdong Musician will have their first live concert tour, called "AKMU Camp", on 21–23 November at Blue Square Samsung Card Hall, Hannam-dong, Seoul.
On 5 November, it was revealed that Suhyun would be a part of the YG Family sub-unit "Hi Suhyun" with Lee Hi. Their debut single, "I'm Different" (Korean: 나는 달라), was released digitally on 11 November.