Song Ji-eun was born on May 5, 1990, in South Korea, she is an only child. Having interest in music when she was young, she auditioned for JYP Entertainment at an early age. While in JYP Entertainment, she sang OSTs of Korean dramas in 2007 and 2008 such as "Learning To Fly" for Air City. Under JYP Entertainment, she was set off to debut as a four-member girl group with Sistar's Hyorin and BESTie's Uji, EXID's Hani, but the plan was scrapped and Song then left JYP Entertainment and joined TS Entertainment.
In December 2009, she sang a duet with Hwanhee titled, "Yesterday".
In 2013, Song released her first single album Hope Torture, which she unveiled at her album showcase at the Olleh Square in Gwanghwamun.
In 2014, Song released her first extended play, titled 25, which contained two singles "Don't Look At Me Like That" and "Pretty Age 25". The same year, Song made her acting debut in the web drama Drawing, Spring, as a part-time worker for a PR team, who loves all living things but has traumatic experience with horses.
In April 2015, Song featured in fantasy youth comedy The Superman Age, an 8 episode series which aired on cable channel tvN. She then starred in the web drama The Immutable Law of First Love, based on a web novel of the same name, playing a Photographer who loves abandoned dogs. In November, she starred in KBS's daily drama Sweet Home, Sweet Honey and received positive reception on her performance.
In September 2016, Song released her second extended play, titled Bobby Doll containing six tracks, including the title track of the same name.
In August 2017, Song submitted a request to the Korean Commercial Arbitration Board to verify that her contract is no longer valid due to TS Entertainment not following the terms of the contract. Song later took to her Instagram where she announced her departure from Secret.
After Secret's success with "Shy Boy", TS Entertainment announced that Song will make her solo comeback with the song "Going Crazy". The song was dubbed as an "emotional ballad track" and "different to what she’s shown through Secret". The single, released in March 2011, was a success and peaked at number one on Gaon Singles Chart, making it Song's and Bang's first number one single in Korea.