Jung Yunho (Korean: 정윤호; born February 6, 1986), better known by his stage name U-Know Yunho (유노윤호) or simply U-Know, is a South Korean singer-songwriter, actor, and a member of the pop duo TVXQ. Born and raised in Gwangju, South Korea, Yunho started his musical training under the talent agency SM Entertainment in 2001 and joined TVXQ in 2003 as the band's leader. Fluent in Korean and Japanese, Yunho has released chart-topping albums throughout Asia as a member of TVXQ. He has made occasional acting appearances in television dramas.
Yunho was born and raised in Gwangju, South Korea. He has one younger sister. Several members of Yunho's family worked in the legal industry, and Yunho's own childhood dream was to be a prosecutor.
When he was in middle school, he and a few other friends formed the dance team A+, and they competed in various dance competitions around the country. After winning a prize at the 1st Annual SM Best Competition in 1999, Yunho signed with S.M. Entertainment and officially started his training in 2001.
His family, who suffered greatly from the 1997 Asian financial crisis, were initially against his decision to become a singer. To provide for himself while he trained in Seoul, Yunho took up various part-time jobs in the city, such as doing snow removal in the morning and working as a waiter at night. He spent most of his high school vacations in Seoul training and only returned to Gwangju for school. Sometime later, Yunho suffered a hormonal imbalance in his throat and underwent surgery, which affected his vocal cords. After losing his voice, Yunho considered giving up his training.
Throughout his years as a trainee, Yunho was put in four temporary groups—all of which later disbanded. In late 2001, at the age of fifteen, Yunho was featured as a rapper and backup dancer in Dana's debut single "Diamond", and briefly toured with her.
In 2002, Yunho was selected to be a backup dancer for Shinhwa and was chosen to be part of the project boy band Four Seasons, which consisted of fellow trainees Kim Jae-joong, Kim Hee-chul, and Kangin. The project group was dropped when Yunho and Jaejoong joined TVXQ in early 2003.
Yunho's stage name "U-Know", a nickname he has been using since high school, reflected Yunho's position as the leader, who was always trying to understand others.
The final line-up of TVXQ consisted of Yunho, Max Changmin, Jaejoong, Park Yoo-chun, and Kim Jun-su. The group officially debuted on December 26, 2003, during a BoA and Britney Spears showcase. They performed their debut single "Hug", which became a hit in South Korea. TVXQ have been releasing number one albums in Korea since their second studio album Rising Sun (2005), which was also the album that gave the group their first Daesang (대상), or Grand Award, at the Mnet KM Music Festival. Their fourth Korean album Mirotic (2008) was the Album of the Year at the 2008 Mnet KM Music Festival and the 2008 Golden Disc Awards. The album features the group's most well-known and best-selling single, "Mirotic".
In 2005, TVXQ made their Japanese debut with the single "Stay with Me Tonight", debuting at number 37 on the Oricon Singles Chart. They grabbed their first number-one single in Japan with "Purple Line" (2008). Their fourth Japanese album The Secret Code spawned two platinum-selling singles "Dōshite Kimi o Suki ni Natte Shimattandarō?" and Share the World" (2009), with the latter being a theme song for the anime One Piece.
TVXQ was plunged into legal turmoil when members Jaejoong, Yoochun, and Junsu filed an injunction against their Korean agency in July 2009. This led to their much-publicized departure from the group in 2010. A year later, Yunho and Changmin returned as a duo, releasing albums in both Korean and Japanese. As a duo, TVXQ set sales records and concert attendance records in Japan, becoming the country's best-selling and highest-grossing foreign music act.
On May 25, 2015, it was announced that Yunho would release his first Japanese solo extended play U Know Y. Consisting of seven tracks, the mini album includes five songs that were previously performed by Yunho during TVXQ's concerts and solo events in Japan. The new track "Burning Down" was selected to be the album's lead single. Bundled with a DVD that includes a music video and behind-the-scenes footage, U Know Y received a limited release, and was only made available for purchase to members of TVXQ's Japanese fanclub, Bigeast. The mini album was released on July 8, 2015.
On July 20, 2015, Yunho releases the music video "Champagne" with then SM Rookie member, Park Jisung, currently a member of NCT.
On May 3, 2019, Yunho announced plans to release his first solo Korean-language album. Yunho's debut extended play, True Colors, was announced on May 28 and was released on June 12 alongside its lead single "Follow".
On December 17, 2020, Yunho announced that he would make his comeback in January 2021. Yunho's second extended play, Noir, was released on January 18, 2021, alongside its lead single "Thank U".
On February 9, 2022, Yunho released his second Japanese extended play You Go Ahead.
On August 7, 2023, Yunho released his third Korean-language extended play Reality Show, alongside its lead single "Vuja De".
On November 5, 2025, Yunho released his first Korean-language studio album I-KNOW.
On July 22, 2026, Yunho released his first single album Time's Tickin', featuring a title track of the same name.