Kim Min-jong began his career on Korean film and television in the 1990s as a matinee idol with a gentle, serious image. He starred in popular TV series that kicked off pre-Hallyu Korean drama trends, notably Feelings, A Faraway Country, Mister Q, Secret and Guardian Angel. He also appeared in the films You Know What, It's a Secret, Resistance of Teenagers, and Park Chan-wook's sophomore effort Trio.
In 1992 he and fellow actor Son Ji-chang launched duo The Blue (더 블루). They were playing leads in hit dramas at the time, and enjoyed explosive popularity among women when they debuted with ballads and dance music. They went their separate ways for a while after their first album, but reunited in 1995 for a second project and produced many chart-toppers.
Kim simultaneously launched a successful career as a solo singer. But in 1996, at the height of his popularity, he announced his retirement from music after one of his hit songs turned out to have been a copy of another Japanese song. He made a comeback two years later with his fourth album.
Though his popularity dimmed in the mid- to late-2000s, Kim remained active in the entertainment industry as an actor, appearing in the film Mr. Butterfly opposite Kim Jung-eun, as well as the romantic comedy/police procedural Woman of Matchless Beauty, Park Jung-geum, risqué cable drama Hyena, period drama The Return of Iljimae, and manhwa adaptation A Man Called God.
In 2009 The Blue returned to the K-pop scene. Kim said Son had been toying with the idea of releasing a "best of" album for a while. When the two appeared together for an event in 2007, the positive response convinced them to get back together, so they re-recorded some of their old hits such as "Feeling Only for You," "With You," and "Endless Love." They released a four-song single album, and during that year went on official The Blue promotional activities. He and Son are also business partners and co-CEO of Blue M Company since 2010.
Kim had a scene-stealing turn as a North Korean agent who defects to South Korea in 2010 spy series Athena: Goddess of War.
In 2012 his management agency SM Entertainment designated him as a non-executive director of one of its subsidiaries, SM Culture & Contents (SM C&C). That same year, he gained new fans after he starred in A Gentleman's Dignity, which portrayed the humorous love lives of a group of close-knit male friends in their forties.After the series ended, Kim and co-star Jang Dong-gun visited refugees in the Republic of the Congo on a mission trip sponsored by UNICEF and UNHCR's World Food Programme. It was televised on SBS documentary program Hope TV.Then he and another co-star Kim Su-ro co-hosted the show My Queen on cable channel Story On, in which they travel the world meeting Korean "queens" who've distinguished themselves in their respective fields.