Born in South Korea to music loving parents, Younha began to play the piano at the age of 4. She developed an interest in Japanese Drama and began to teach herself Japanese. Before long, she was skilled enough to interpret to her school friends what would happen on Japanese television. What began as an interest in Japanese dramas developed into an interest in Japanese music. At the recommendation of an older student in her school's broadcasting club, she listened to such artists as Utada Hikaru and Misia and soon began to like Japanese music. Younha began to dream about debuting as singer alongside her favorite artists.

In order to realize her dream, she began to seek out auditions within Korea. She claimed that she went through as many as 20 auditions. She also commented in her interview that certain companies refused to sign her to their labels because they believed she was not "pretty" enough, although she sang pretty well. Her mother also discouraged her dream and even locked her bedroom door to prevent Younha from leaving the house. Younha, however, climbed out the window and made it to the audition anyhow. At one audition, she made an overwhelming impression and signed a contract with a Korean company. Soon after, Younha's voice was heard by a company in Japan. In order to make her childhood dream of debuting in Japan come true, Younha underwent recording while going back and forth between Korea and Japan. Quickly, Younha's Japanese skills advanced so much that she surprised even the staff around her.

After a TV drama producer heard her demo tape, her single, "Yubikiri", was chosen as the insert song for the Fuji TV Monday drama Tokyo Wankei Destiny of Love. In October of that same year, she debuted with her official first single, "Yubikiri -Japanese version-".

Younha's second single, "Houkiboshi", was used as an ending song for the popular TV anime Bleach. It became a hit, debuting on the Oricon chart at #15, and propelled Younha into the limelight. Between "Touch/Yume no Tsuzuki" and "Houkiboshi", she released "Motto Futari De". It flopped massively, only reaching #117 on the Oricon Charts due to no promotion. Her later single, "Touch/Yume no Tsuzuki", first charted at the #14, with the tie-in. Her first album Go! Younha reached the #12 spot on the weekly charts. Younha is the second female Korean after BoA to reach the top 20 on the Oricon album charts.

My Lover was a re-cut single from Go! Younha, her debut album, and was re-cut because it was the theme to the Bleach GC: Tasogare Ni Mamieru Shinigami. It was limited to 70,000 copies and flopped, selling only about 2 000 copies, ranking at #58. Younha was also chosen to sing the ending theme to the TV anime Jyu Oh Sei (獣王星 . The single, "Te wo Tsunaide" only did slightly better than "My Lover", just making it into the top 50 at #50. "Ima ga Daisuki" (今が大好き was released, with more live performances than "Te wo Tsunaide", and a tie-in, and a slightly less rocky style than "Te wo Tsunaide", and more like "Motto Futari De". It seemed that Younha has a bigger budget on this single. It did significantly worse, as her 2nd worst ranking single, at #71.

Younha was once again chosen to be an anime theme songstress for Kiba. The song "Hakanaku Tsuyoku" (儚く強く was used as the second opening for the show. The single was released on January 17, 2007. This single, unlike her other singles, has only 3 tracks. Surprisingly, this single appeared on the Top 20 Daily Charts for exactly one day, at #16. The Weekly rank was at an above-average #36, but sales were only slightly better.

Younha released a digital Korean single titled "Audition". The single includes "Audition (Time 2 Rock)", a pop-rock song and "Waiting" (기다리다 , a ballad. Although it was released as a digital single, very limited hard copies of the single were available as well.