It was announced in late November that Kara would be releasing a second mini-album, two months after "Rock U", with a fun "party" concept. After the song's release and the positive reception that it received the group's name became a popular search term on various Korean portal sites propelling the girl's popularity in South Korea.
In addition, the song also charted high on various websites and digital music retailers, which allowed the group to rival some of South Korea's top girl groups such as Wonder Girls, Girls' Generation, and the Brown Eyed Girls. The group's leader, Park Gyu-ri, attributed Kara's rise in popularity to their natural but pretty appeal, while national newspaper Sports Seoul attributed it to the fact that the band finally found their own identity.
The group began its comeback on all major music shows on December 4, 2008, the single's release date, starting with M.Net Countdown. During their first national performance on KBS's Music Bank, member Goo Ha Ra forgot part of the choreography and cried for an hour backstage.
During Kara's December 14, 2008 performance on Seoul Broadcasting System's Inkigayo ("Popular Songs"), the fans decided to cheer with pink rubber gloves, which positively surprised viewers; even the group was surprised, as member Han Seung-yeon wrote on her blog that she almost died of laughter.
On November 29, 2008, DSP Entertainment released a teaser video for "Pretty Girl", which received over 40,000 hits in one day. The full video was released on December 2, 2008 online and was positively received by the public.