Kim Nam-joo started modeling in 1992 after joining the Miss Korea pageant when she was a college sophomore. She then placed fourth in an SBS talent search, which opened the door to acting for her. She quickly rose to fame with her hit dramas such as SBS’s City Men and Women in 1996 and Model in 1997. In 2001, she starred in the MBC drama Her House, which won her a Top Excellence Award at the MBC Drama Awards. After going into semi-retirement for several years, she made a successful TV comeback with MBC’s Queen of Housewives in 2009. She collected numerous accolades for her work in the series, including Best Actress at the 46th Baeksang Arts Awards. In 2010, she returned for the Housewives spin-off, Queen of Reversals. In 2012, she acted alongside Yoo Joon-sang and Yoon Yeo-jung in the KBS2 weekend family drama You Who Rolled in Unexpectedly, which gave her multiple Daesangs. In 2018, she worked with Ji Jin-hee in the JTBC melo-thriller Misty, which scored her another Baeksang Best Actress trophy.

Kim Nam-joo married actor Kim Seung-woo in May 2005. She gave birth to a daughter in November of the same year. Their second child, a son, was born in March 2008.