Gummy debuted in 2003 with her album Like Them. Due to the success of other label mates, Her second studio album, It's Different, was released on September 9, 2004. Her title track Memory Loss (기억상실) brought her success and recognition and led Gummy to win the Bonsang at the 19th Golden Disk Awards. The same year, Gummy earned at the 2004 Mnet Km Music Festival for Mobile Popularity Award for Memory Loss.
She released her fourth album titled Comfort on March 12, 2008, and it is her first released in three years. The album was postponed several times because Gummy wanted to release a high-quality album that showed her growth as an artist. The lead single I'm Sorry (미안해요) features T.O.P from Big Bang; he is also featured in the music video, along with Sandara Park from 2NE1. A week after its release, the song peaked within the top five spots on various digital charts.
On April 12, 2010, YG Entertainment announced comeback plan for Gummy and her fellow label mates Big Bang, 2NE1, and Se7en. A week later, it was revealed that Gummy is coming back with a mini album titled Loveless. A music video plus the full song of one of her tracks in the mini album was released on April 21. Loveless was released on April 29, and promotion for the album began in May. She had released a music video for multiple songs since the album such as "There Is No Love", which had already been performed live.
After staying in Japan for several years to improve her Japanese and to get a sense of the culture, Gummy finally felt confident in her Japanese to debut. On October 15, 2011, the MV for her remake of "I'm Sorry" feat. TOP was released.
2013: 10th anniversary, Snow Flower OST, 2nd Japanese Mini Album and Contract expiry
2013 marked the tenth anniversary for Gummy and she celebrated with a fan meeting.
Gummy released her OST for the Korean drama, That Winter, the Wind Blows. "Snow Flower" was a hit and ranked high on charts such a Gaon and Instiz. Gummy performed "Snow Flower" on the music show Inkigayo.
Gummy also released her second Japanese album, Fate(s). Gummy directly participated in the production of the album in Japan, and she sought the help of producer Jeff Miyahara, who has produced songs for Amuro Namie, V6, KAT-TUN, and other popular Japanese artists. Gummy also had a duet with fellow label mate Daesung from BIGBANG. Two music videos were released for the lead single off the album, "Shinjiteru (Believe)".