Sunji Lee (이선지) is a pianist, composer and producer in Seoul who has won the Korean Music Award for the best jazz album twice, for The Night of the Border in 2015 and for Song of April in 2019. Korean newspapers write her name 이선지 and her records are credited Sunji Lee; the spellings Lee Seon-ji and Lee Sun-ji appear in award lists and festival programmes. Her date and place of birth are not published. She has led her own records since 2008, writes most of her own material, and in recent years has moved from piano trios and string suites toward solo piano with synthesizers while still describing jazz as the foundation of her music.

She came to jazz by a roundabout route. Hankook Ilbo's 2014 feature says she studied French literature at Chonnam National University in Gwangju, where a campus rock band introduced her to jazz, and that after graduating she entered the Seoul Institute of the Arts and, with no jazz teacher available, played in a trio that worked only through standards from the Real Book. Her release notes date the Seoul Institute of the Arts course to 1997 and add a graduate degree in practical music at Dongduk Women's University in 2002, which she took to study jazz composition in earnest. In 2005 she left for the United States. She spent three years there, one semester at the Berklee College of Music in Boston and the rest in the jazz programme at New York University, where, according to the newspaper, she studied piano with the trumpeter Ralph Alessi and composition with Gil Goldstein. Her own release notes name Don Friedman and Andy Milne among her teachers and say she played in clubs in New York and Brooklyn, and that in 2008 she took part in a workshop at the School for Improvised Music in Brooklyn and received a scholarship for the most creative player. The liner notes of her first album, written by the critic Kim Hyun-joon, add that she has played with Billy Drummond, George Garzone and Joe Lovano. She settled in Korea in 2008. Her release notes list teaching posts at the Seoul Institute of the Arts, Dongduk Women's University, Dong-ah Institute of Media and Arts and Howon University, and Howon's practical music department lists her as an associate professor of piano.

Her first record as leader, The Swimmer, was released on December 18, 2008. It is a quartet record with Alessi on trumpet, Ben Street on bass and Mark Ferber on drums; three of its nine pieces are for piano trio, and all but Cole Porter's "So in Love" are her own. Alessi is quoted in the release text describing her music as unusually original in contemporary jazz, and her later release notes say she performed with him on the EBS Space television series. Summer Ends followed on May 27, 2010, a piano trio record with a cello added and string arrangements; Hankook Ilbo names Jung Yong-do on bass, Sam Pickler on drums and the cellist Choi Jeong-wook, and the release text says every piece but "Nefertiti" is her own. In 2011 she won the Best Creativity prize at the fifth Jarasum International Jazz Competition, according to the notes for her third album. Soar came out on May 22, 2012 on the Audioguy label. It pairs her piano with two saxophonists, Sungwan Kim and Sungjoon Kim, over bass by Inyoung Kim and drums by Han Woongwon (names as spelled on Discogs); Hankook Ilbo says the two altos are set left and right. The album was nominated for the best jazz album at the 10th Korean Music Awards, and the release concert took place at Pan Theatre in Hongdae on June 3, 2012. By then she was also playing in the Seoul Meets Free Music Orchestra and in a band led by Jang Gi-ho.

The Night of the Border (June 2, 2014) was her fourth leader album. Hankook Ilbo reports that she produced it entirely herself, down to the mastering. Its eight pieces are all her own, played with a guitar added to the saxophone and rhythm section: the saxophonist Kim Sung-joon, the guitarist Oh Jin-won, the bassist Kim In-young and the drummer Kim Yoon-tae. The release text calls some of the pieces, "Dive" and "Vibe" among them, rock-coloured and others, "You Float, You Weave" and "Darkside of the Moon" among them, very free. It won the jazz album category at the 12th Korean Music Awards, held at Mapo Arts Center on February 26, 2015. In 2014 she gave a pub-night concert at the Daelim Museum in June and a concert at Pomtek Works Hall in Hapjeong on September 5. The newspaper noted that the album had sold quietly and that she was already talking about a next record with a more Korean sensibility, built around empty space and han, the long-held sorrow of Korean culture.

On April 28, 2016 she released Folksongs with the bassist Jinju Jang, a duo concert recorded in the Stradeum studio on a Bosendorfer piano. The programme mixes Korean songs, among them "Arirang", with spirituals, "Shenandoah" and two of her own pieces; the release notes add that she had been named pianist of the year in a readers' poll the year before. In October 2017 the first Seoul Forest Jazz Festival billed the Lee Sun Ji Trio with Doe Jae-myoung, whose EP A True Travel (2018) lists her too, and in October 2018 the festival's second edition listed her trio together with Peter Evans.

Song of April appeared on April 6, 2018 on Pageturner Music, distributed by Cross Dissolve. Kim Hyun-joon's liner note describes it as a dedication and a confession written over several years in the aftermath of the Sewol ferry disaster of April 2014, in two suites, "Song of April" and "Song of Bird", the second built on the folk song "Saeya Saeya". Two violins and a cello join her trio of Lee Jun-sam on bass and Shin Seung-gyu on drums. Bugs, the Korean streaming service, named it its album of the month for May 2018, and it won the best jazz album category at the 16th Korean Music Awards at Guro Arts Valley on February 26, 2019.

After that her releases became more varied. She issued the singles "GLINT" and "snow" in 2019 and 2020 and the album Oscillations on September 1, 2021. Oscillations is mostly solo piano, synthesizers, ambient textures and electronics, with Lee Jun-sam on bass and Shin Seung-gyu on drums on several pieces and her student Surim singing "lost". In an interview with Melon she said that listeners knew her from earlier albums such as The Night of the Border and Song of April, that the Covid period had given her time to go deeper into the minimalist and electronic music she had admired from a distance, and that jazz remained the foundation of her music. With the folk singer Hwang Pu-ha she made the EP Reply, piano and voice, released on September 26, 2021, and with Park So-yu, who programs the drums, bass and sound effects, she formed the duo Intersection, which released singles in 2021 and 2022. In 2022 she began a series of solo piano pieces on a felt-muted piano, Music for Peace, and contributed three tracks to Canon, a five-pianist album produced by Kim Hyun-joon, with Jaehun Kang among the other pianists.

She also writes and produces for others. She produced and arranged the singer Jo Jeong-hee's Songs and Lullabies (2021), whose first half is voice and her piano alone, and she composed and arranged six of the nine songs on Jo's Each Flower (Mirrorball Music, 2023), playing piano and keyboards. She composed and arranged "One More Step" (2024) for the Naver webtoon Haeilo's Morning.

Eternal, released on September 7, 2024 under the name Sunji Lee Quintet, put her piano and synthesizer with the trumpeter Han Dong-ho, the guitarist Lee Su-jin, the bassist Kim Hyun-gyu and the drummer Lee Seok-hyeon, with liner notes by the poet and singer Lee Rin-a. It was one of five nominees for best jazz instrumental album at the 22nd Korean Music Awards on February 27, 2025, the year Jihye Lee's Infinite Connections won. Her trio played the midnight concert at the Gyechon Classic Festival in Pyeongchang, held May 31 to June 2, 2024, and on February 17, 2026 she released RE:breath, an EP of four pieces for piano and electronics, three of them reworked from her own earlier pieces.

Lee told Hankook Ilbo that she starts a piece from a picture or a story and thinks in film-like colours, and that her music is jazz because the improvisation is strong and because she plays her own tunes rather than standards. From a teacher of her American years she took the advice to play a piece differently every time, even after a hundred performances. She says she learned from Alessi, a free-jazz specialist in the newspaper's words, to let a line develop intuitively without being bound to the chord changes, a natural flow and not disorder. Kim Hyun-joon described Soar as impressive enough to be called a stylist's finished form, and the newspaper singled out the cello, a rare sound in jazz, on Summer Ends. Her records often add colour from outside the standard rhythm section: a cello, a guitar, a string trio, a second alto saxophone.

The material has two sides. In the albums from The Swimmer to Song of April she writes modern jazz, with carefully worked compositions, strings and an interest in Korean themes: folk songs on Folksongs, the old song "Saeya Saeya" on Song of April. Since Oscillations she has worked more with synthesizers and minimal, ambient writing. In the Melon interview she named Arvo Part, Nils Frahm, Olafur Arnalds, Ryuichi Sakamoto and Thom Yorke as influences on that turn. The streaming service Bugs files Oscillations under crossover jazz and the 2026 EP under neo-classical. Even so, her awards, her festival appearances, her teaching in a practical music department and the quintet and trio work of Eternal keep her inside the Korean jazz scene.