Park won several singing contests in the United States before recording a Gospel album in 1993. She continued her studies while doing many performances. She attended UCLA for a year before she began her career as a singer, beginning with her first Korean album Piece in 1998. Park's first album sold more than 500,000 copies, even though she wasn't comfortable enough to do promotions on talk shows. She did not speak Korean very well until she released her first album. In 1999, A Second Helping was released. It also was well received by both fans and the critics. Park's third album, "Naturally", was mixed in both South Korea and the United States.
After a yearlong break from singing because of her studies in the United States, she came back in 2002 with her album called Op.4. More comfortable with the media, she became much more accessible for talk shows and performances. In 2002, her song "꿈에" (In a Dream) was a big success and enabled her to enter foreign markets, such as Singapore. The South Korean government select Park to represent South Korea in the opening and closing ceremonies of the 2002 FIFA World Cup. At the end of 2002, a "best of" album was released and she played a series of concerts. Live recordings from these concerts were compiled into her first special live album in CDs and DVD. Park, along with Brown Eyes, CHEMISTRY, and Sowelu, formed the special unit conveniently called "Voices of Korea/Japan" and made the title song for the 2002 FIFA World Cup Official Album – Songs of Korea/Japan. She later debuted in the Japanese music industry where she received moderate success.  She is especially proud of her fifth Korean language album, On & On, because she felt that she was finally comfortable and confident singing and composing in Korean. It took her about two years to make the album and, during that time, she became very involved with the production and creative work behind the album; she helped with many of the song arrangements, played the piano and guitar for some of the tracks, and composed four of the songs on the album. In 2007, she performed the opening theme Inori~You Raise Me Up～(祈り～You Raise Me Up～?) of the Japanese anime TV series Romeo x Juliet, which is a Japanese cover of Rolf Lovland and Brendan Graham's song You Raise Me Up. The single also includes a cover of the English version. Her sixth Korean language album, Come To Where I Am, was released on December 11, 2007. All songs were written and produced by Park herself.
After announcing the release of her eighth studio album, videos of her with composers she was working with for her album introducing her songs were released online. Shortly after, on June 19, 2012, her album was released with the title track, "Sorry" (Korean: 미안해), being a cover of the Spanish language song Mientes by Mexican pop band Camila.