He made his debut in 2003 with the studio album Just Listen, which sold over 210,000 copies by the end of the year and spawned the hit single "Come Back to Me".

His next Korean singles, "Better Together" (2010) and "When I Can't Sing" (2012), reached the top five on the Gaon Digital Chart in South Korea.

[11] Must Listen peaked at number one on the monthly Recording Industry Association of Korea album chart.

[15] In April 2005, Seven continued promotions for Must Listen in Thailand, where the album sold over 100,000 copies and the singles "Passion" and "Tattoo" topped the Channel V weekly charts.

[17] On January 9, 2006, Seven released his first Chinese album, Must Listen (不得不聽), in China, Hong Kong, Taiwan, Malaysia and Singapore.

He played three new songs, which featured collaborations with producer Rodney "Darkchild" Jerkins and hip-hop group Three 6 Mafia.

[28] On March 10, 2009, Seven released his first English-language single, "Girls," a pop-R&B song that features American rapper Lil' Kim.

Seven began his follow up promotions in October with the song 'I'm Going Crazy' which featured his longtime girlfriend Park Han-byul as the main actress in the music video.

[33] On March 18, 2013, Seven enlisted for his mandatory military service at the 306 Reserve in Uijeongbu, Gyeonggi Province for five weeks of basic training followed by 21 months as an active-duty soldier.

On October 14, he released the mini-album I Am Seven (stylized I Am Se7en), his first album in over four years, along with the lead single, "Give It to Me", and its music video.

[37] After staying out of the public eye for four years, Seven announced he would return to promote in Korea after signing a new contract with Dmost Entertainment on April 17, 2020.

[39] In September 2016, news outlet Sports Chosen reported that Seven and actress Lee Da-hae had been dating for over a year.

[42] In July 2013, Seven, alongside singer Sangchu of Mighty Mouth, was found guilty of visiting a massage parlor that provides sexual services while he was on military leave to perform at a concert that June.