Yujin Kim (김유진) is a South Korean jazz singer-songwriter from Incheon who writes every song she records, with lyrics in Korean, English, German and Portuguese. Her first full-length album, A Piece and the Whole (한 조각 그리고 전체, 2022), won Best Jazz Vocal Album at the 20th Korean Music Awards, held on March 5, 2023, and her second, Extraordinary (2023), won the same prize at the 21st, on February 29, 2024. Kyeongin Ilbo reported that she was the first artist to take that category two years running. English-language pages for the awards romanize her name as Kim Yu-jin; her albums, streaming pages and album credits use Yujin Kim, the form used here.

She was born in 1997 in Gyeyang-gu, Incheon, and grew up there and in the Geomdan area of Seo-gu before her family moved to Yangju and then to Gimpo for high school. A church praise team in Geomdan led her to singing and piano, and as a child she attended the Seo-gu English Village and an English camp at the Incheon English Village; she has named those English villages as the biggest influence of her Incheon years, because they gave her a taste for learning languages and talking with people who speak them. In the second year of middle school she heard Norah Jones's "Don't Know Why" on the radio, looked the singer up, and began tracking down jazz records and working out the scores at the piano. Her parents were against formal lessons once she reached high school, so she wrote them letters and won a prize at a Gyeonggi youth arts festival, and at 18 she was allowed to take lessons in the subject.

In 2016 she entered the practical music department of Seoul Institute of the Arts as a vocal major, and she graduated in 2023. Few students in the department played jazz, she has said, so a small group formed and played together in clubs, and from the age of 20 she also worked weddings and hotel lounges. Her published biography lists her as leader and vocalist of the Yujin Kim Quintet and Sextet at clubs including Once in a Blue Moon, Positive Zero Lounge and Spinning Wolf. During those years she spent time in Germany through an Ausbildung program, a vocational training scheme she describes as a working holiday rather than music study; she worked in a drugstore there. On January 26, 2018 she released the duo EP Four Strokes with the pianist Han Gyu-ho (한규호, billed as Kyuho Han on streaming services), and she later wrote the words and music of "괜찮은 이유," sung with Sunwoo Jung-a (선우정아), for Kind of Yellow, an anniversary compilation from the Seongsu-dong club Positive Zero Lounge.

A Piece and the Whole was recorded on October 11, 2021 at Yagi Studio, mixed and mastered by David Darlington at Bass Hit Recording in New York, and issued by Sori-e Naite Music Company on streaming services on March 30, 2022, with a CD dated the next day; the sleeve carries the German subtitle "1st Ein Stück, Das Ganze." Its eight songs are all her own. The pianist Eunji Im, the bassist Inseop Song (who shares the music director credit with her), the drummer Kim Yeong-jin, the saxophonist and clarinettist Hachul Song, the flutist Jieun Park and the guitarist Junho Song play on it. In her own notes she dates the songs from 2016 to 2021: the title song, written in July 2021, is about lives that look scattered but form one whole, "Es ist gut Hause zu sein" (August 2019) is about coming home from a hospital stay, "Portugal" is sung in Portuguese, and "사라지는 것들을 향한 애정" has no lyrics. The critic Jeong Byeong-uk wrote the liner essay, describing a mix of ballads, instrumental solos, swing and Brazilian rhythm that settles into warm but firm pop. Kyeongin Ilbo's 2024 profile lists it among the "albums of the year" picked by 11 critics at Hankook Ilbo for 2022, and the awards committee, as the same paper reports, called it a daring debut statement. She was also a Rookie of the Year nominee at the 20th awards, and Jazz People named her a rising star in the vocal category in 2023. She told an interviewer from Poclanos that she had not imagined even being nominated and that when the awards office phoned ahead to tell her she had won, she asked whether they were joking.

Extraordinary followed on November 14, 2023: nine songs, again all her own, produced with Eunji Im. Inseop Song (bass), Hayeon Song (drums), a saxophonist credited as 이수정 and Junho Song (guitar) joined her; Jiyeop Kim recorded it at Eumsound, Darlington mixed and mastered it, Han Seokgyu designed the cover and Abi Raymaker took the photographs. Its themes are diversity, equality and coexistence. "Evolve" hopes for a society that respects difference, "Whisper of Devil" takes its starting point from Wagner's Tristan und Isolde and adds rock colour, and the title song, which she began writing in her teens, is about the uniqueness of each person. Kyeongin Ilbo described the record as fusing pop, rock and Latin music within jazz grammar. At the 21st Korean Music Awards it beat nominees that included Carina Nebula, Moon Mi-hyang, Sunny Kim with Vardan Ovsepian and Ben Monder, and Song Yi-jeon with Ovsepian.

On June 29, 2024 she gave her first solo concert, at Bello Zoo in Hongdae, Seoul. By November of that year she had also played the Seoul Jazz Festival and the Seoul Forest Jazz Festival, and she was due to appear at the RSS Festival that month. Her third release, the eight-song dudndudndudn (2024), which she calls her 2.5th album, came out on October 2, 2024, with release concerts on October 11 and 12 at Bottom Line, the oldest jazz club in Incheon. The title is meant to be read in Korean as "ddudun ddudun ddudun," a spell she invented for making wishes come true. She wrote most of it while travelling in Greece in October 2023 and Portugal in March 2024, produced it with Eunji Im and Junho Song, recorded the instruments at RSS Studio in Ilsan, and wrote about love, longing and a sense of lack; "Saudade" appears in a studio version and an acoustic version recorded at Song's home studio, Hayane's Room. She has said she works without a management company, and her albums are self-produced and released through Poclanos. In 2025 she was a featured singer on "Butterfly" and "Nightcap" on the ACT EP by Ologi and Heibe (January 27) and on "Visiting me" on WYK? by Zerowho (October 1).

She defines herself as a jazz singer-songwriter rather than a jazz vocalist, because she builds her own material on a jazz foundation, and she told Poclanos that jazz, pop, R&B and hip-hop cannot be pulled apart in her mind. Kyeongin Ilbo quotes her saying that most debut albums by jazz singers reinterpret standards, and that she believes her original songs, with a jazz colour and a songwriter's colour together, are what the awards committee rewarded. Her first record is about connection, her second about each person's uniqueness, and the third turns to private feeling. In one song on Extraordinary, "Continuum," the rhythm, key and groove keep changing while the first and last chords are the same, which she meant as a picture of staying herself through many changes.

The sound ranges from piano-led jazz ballads with scat and swing on A Piece and the Whole to the pop and rock colour of Extraordinary, and then to the jazz-pop of dudndudndudn, a record that a Poclanos writer says has jazz in it but is closer to a pop album. Streaming services file that third release under pop or R&B and soul, and she describes her aim as being a musician without boundaries. The standard she links with Incheon is "Blue Skies," and her way into jazz was Norah Jones.