They debuted on 8 April 2011 with the single album The Difference. The songs “Do You Know (Hangul: 아나요)” and “So Sexy” were their promotional singles for the album. On 29 July, they made their comeback with reggae song “Easily (Hangul: 툭하면)” from their mini album Back to da Future. The group promoted a remix version of “Easily” on 13 August and released it on 26 August. They made an appearance on Jay Park’s Mr. Idol movie.
On 14 March, Eun-young was revealed a member and the leader of the group. She is the niece of Shin Ha-kyun, an actor known for his role in Welcome to Dongmakgol and Sympathy for Lady Vengeance. Hye-ran was revealed on 17 March and gained attention because of her resemblance to singer Son Dambi and old dance rehearsal videos that led to her name being feature on video sites like M. Goon. Ye-jin became the third member to be revealed. She also gained attention because of her past as she was ‘Miss Seattle’ at the Miss Korea competition and her resemblance to actress Kim Sa-rang. Seo-a became the fourth member of the group. She was previously a model before joining the group.
On 31 March, Brave Brothers unveiled two images of the group that provided two concepts (a sexy chic and colorful eccentric) which the group will be performing with. Two teasers were released of “So Sexy” and “Do You Know” in the first week of April. On 7 April, they released their debut single album The Difference along with the music video of “Do You Know”. They made their debut on Korean Broadcasting System’s (KBS) Music Bank with “So Sexy” and “Do You Know”. On 24 April, they appeared on Gag Concert and performed a trot version of “Do You Know”. Eun-young appeared on KBS's 100 Points out of 100 show and won 2 medals (Gold and Bronze) on the show. The music video for “So Sexy” was released on 8 June. They had a cameo appearance along with Superkidd on the Seoul Broadcasting System (SBS) drama, Protect the Boss. On 22 July, Brave Entertainment announced that the group would make a comeback during the month and shared concept photos of their mini-album Back to Da Future. Their title track, "Easily" featuring Korean reggae artist Skul1, was revealed along with the music video. Brave Brothers stated that the song was homage to Kim Gun-mo’s “Excuse”. A teaser for the music video was revealed on 27 July. One day later, the music video was released before releasing their mini-album on the following day. They made their comeback on Music Bank with the song “Easily”. The group participated at the 3rd Idol Star Athletics Championship on 13 September. They had a cameo appearance in Mr. Idol with Chocolat and other idol groups. At the 19th Korea Culture Entertainment Awards on 15 December, the group received Rookie of the Year award in the Idol Music within the song category. On 25 December 2011, they appeared on KBS 2TV's Let’s Go Dream Team! as special guests and performed for contestants of the show.
On 22 February, Brave Girls release their mini-album Re-Issue on along with holding a show case with guest performance from Teen Top. The title song "Nowadays" charted high on some charts and became one of the most searched topic. Instead of a "sexy" or "cute" concept, Brave Girls sported a masculine concept. The members said, “We think that we really need to show a different side of us. We understand that fans who waited for our sexy or cute concept might be disappointed, but hope that they would like this concept too.” Brave Girls made their first comeback stage on Mnet’s M! Countdown.
On 29 August, 2013, it was announced that Brave Girls will have a comeback in the fall, with a new song entitled "For You".