The original 2012 eight-member line-up included: Choa, Jimin, Yuna, Youkyung, Hyejeong, Mina, Seolhyun, and Dohwa.

AOA began their career simultaneously promoting as a dance group and band, and officially debuted in July 2012 with the release of the single album Angel's Story.

In early 2013, the band unit AOA Black released their official single titled "MOYA" to moderate success.

Among the groups' biggest hits are "Miniskirt", "Short Hair", "Like a Cat", "Heart Attack", "Give Me the Love", "Good Luck", "Excuse Me", and "Bingle Bangle".

The eight members were introduced individually through teaser photos from July 16 to 23 (in order: Seolhyun, Choa, Hyejeong, Dohwa, Yuna, Mina, Jimin, & Youkyung).

Explaining the concept of their debut, FNC revealed that seven members are "full angels": Seolhyunari[5] (Seolhyun), Choaya[6] (Choa), Hyejeong.Linus[7] (Hyejeong), Chanmi T.T[8] (Dohwa), Yunaria[9] (Yuna), Minaring[10] (Mina), and leader Jiminel[11] (Jimin), while Youkyung (or "Y") is listed as a "half-angel/half-mortal" as she is only a member when the group promotes as a band, thus they were known as a "7+1" group.

Two months after their debut, FNC confirmed that the group would be making a comeback with a second single album "Wanna Be" on October 10.

[13] Hyejeong, Jimin, Choa, Yuna, Dohwa, Mina, Seolhyun and Youkyung dressed as characters from Kill Bill, Léon, Legally Blonde, Tomb Raider, Harry Potter, Breakfast at Tiffany's, Romeo and Juliet, and The Fifth Element respectively.

[14] AOA Black made their first comeback appearance on the October 10 broadcast of KM's Music Triangle and performed the band version of "Get Out" for the first time.

[24] In May that year, AOA appeared on Real Man to perform their hit song and play a quiz showdown with the soldiers.

[27] Due to their rising popularity, AOA released their first Japanese single, a Japanese-language version of their hit song "Miniskirt" on October 1.

'[28] In late October, FNC announced that AOA would be having another comeback, and shortly afterwards, began releasing teasers for the music video, unveiling a darker Catwoman concept.

Seolhyun was chosen to host the 2015 KBS Entertainment Awards alongside comedian Shin Dong-yup and singer Sung Si-kyung.

[41] On January 31, 2016, FNC formed a new sub-unit called AOA Cream, composed of members Yuna, Hyejeong, and Dohwa.

[citation needed] On March 3, it was announced that "Give Me the Love", AOA's fourth and first original Japanese single, would be released on April 20.

The track list comprised title track "Give Me the Love" featuring Japanese singer Takanori Nishikawa, a Japanese version of "Girl's Heart" and a new original song titled "Still Falls the Rain" [42] On April 12, AOA aired their reality show "Channel AOA" on OnStyle Live.

[43] The group came under widespread scrutiny following their appearance on the reality show when members Jimin and Seolhyun failed to recognize An Jung-geun in a game challenge they had performed on the series.

In November, AOA released their second Japanese album Runway, which includes all songs from their previous "Give Me the Love" single.

[56] The album's single peaked at #4 on Gaon Digital Chart and the group received a Bonsang at the Soribada Best K-Music Awards.

[57] FNC responded to reports shortly after stating that contract negotiations with the members were ongoing and discussions about resigning were going positively.

[60][61] The series began airing on August 29, and following the premiere, AOA had begun to receive a lot of positive reception and widespread attention for their appearances on the show.

[66] In early July 2020, former member Mina made a series of Instagram posts, in which she alleged that Jimin had bullied her for ten years, driving her to the point of self-harming and attempting suicide.