Joonsam is a South Korean double bassist and composer who grew up and trained in Seoul and has lived in New York since 2007. He performs under a single name; Discogs gives his real name as Joonsam Lee, and a 2014 concert listing, his distributor's biography and the Jazz Music Archives biography all use Joonsam Lee. His one release under his own name is A Door (Origin Records, 2016), a debut that gathers a cast of New York players around a piano trio and was nominated at the 15th Korean Music Awards in 2018. No birth date and no Korean-script form of his name have been published.

The Jazz Music Archives biography, which describes him as born and raised in Seoul, says he began on electric bass at nineteen after hearing Jaco Pastorius and switched to acoustic bass two years later, naming Ray Brown, Paul Chambers, Christian McBride and Avishai Cohen as influences. In Seoul he studied classical bass with Yeong-Seok Seong of the Seoul National Symphony Orchestra, and at the same time played in the jazz band of the drummer Yeon Namgung, on television, on radio and in concert halls. DownBeat likewise calls him a classically trained bassist from Seoul.

In 2007 he moved to New York to study at New York University. The same biography lists, among the teachers and musicians he studied and played with there, Joe Lovano, Brian Lynch, Ralph Alessi, Kenny Werner, John Scofield, Don Friedman and Jean-Michel Pilc, and says he graduated with a master's degree and then became busy performing and recording in the city. His distributor, Challenge Records, describes the debut's compositions as pieces written since the move that reflect the range of settings he had worked in, from concerts with his own trio to symphony performances, international tours and club work in New York. A listing for a free concert at Theater for the New City in Manhattan on August 27, 2014 billed the Joonsam Lee Trio with the guitarist Pasquale Grasso and the drummer Sharif Zaben.

A Door was recorded on May 10, 2014. Discogs credits Aaron Parks on piano and Nate Wood on drums as the core trio, with Joonsam credited for bass and for composing; Andy Taub recorded it, David Darlington mixed it and Wood mastered it. Around the trio, the trumpeter Ralph Alessi plays on tracks 1, 4, 5, 7 and 8, the guitarist Ben Monder on "Zadrak" and "Where Water Comes Together with Other Water," and Yvonnick Prene on harmonica on "Boa Noite." Yeahwon Shin sings on "Love Trauma," described by DownBeat as wordless vocals. Chung Eun Han plays bamboo flute on "Doraji The Flower," per DownBeat the only piece on the record not written by Joonsam: a traditional Korean song. The CD came out on Origin Records (catalog 82716); Apple Music dates the digital release to June 17, 2016, and Challenge Records lists the CD for September 2, 2016.

Reviews were favorable and appeared in several places. Izzy Yellen's DownBeat review of July 2016 called it eclectic and relaxing, heard orchestral textures with echoes of symphonic music and Korean folk song, and noted that the album is a trio at heart but changes its instrumentation from track to track. C. Michael Bailey wrote about it in All About Jazz on March 1, 2017, in a column of short reviews, picking out "Zadrak" and "Where Water Comes Together with Other Water," the two Monder tracks, as the centerpieces of a far-ranging set; Jazzwise also published a review of the album.

On February 6, 2018 the organizers of the 15th Korean Music Awards announced that A Door was nominated in two jazz categories, Best Jazz Album and Best Jazz and Crossover Performance. The Best Jazz Album field also included Youn Sun Nah and a duo album by Sunny Kim and Ben Monder. At the ceremony in Seoul on February 28, 2018 the album prize went to the Lee Ji-yeon Contemporary Jazz Orchestra's Feather, Dream Drop and the performance prize to the Hogyu Hwang Quartet's Straight, No Chaser. A Jazz Music Archives snapshot from 2019 says he lives in New York. No later releases, and no current activity, have been published.

His playing and writing combine a classical bassist's schooling with New York post-bop. Jazz Music Archives files him under post-fusion contemporary jazz, and DownBeat's reviewer described an album built around orchestral textures, with echoes of symphonic music and Korean folk song. The one folk piece on the record, "Doraji The Flower," is a traditional Korean song and features Chung Eun Han's bamboo flute. The album moves among piano trio settings, trumpet and guitar features, a vocal piece and two short interludes, "23451" and "23452," each under a minute. Discogs lists it under Jazz with no further style tags. The influences named in the Jazz Music Archives biography run from Jaco Pastorius to Ray Brown, Paul Chambers, Christian McBride and Avishai Cohen.