Joon Hyun Kim is an American attorney who served as the acting United States Attorney for the Southern District of New York from March 2017 to January 2018. He was Deputy U.S. Attorney for the Southern District of New York from July 2015 to March 2017 after serving as the chief of the criminal division since July 2014. From April 2013 to July 2014, Kim was the chief counsel to the U.S. Attorney. In March 2021, Kim was chosen by New York Attorney General Letitia James as independent counsel, along with Anne L. Clark, to co-lead the investigation into sexual harassment claims made against New York Governor Andrew Cuomo.

The United States attorney for the Southern District of New York is the chief federal law enforcement officer in eight New York counties: New York (Manhattan), Bronx, Westchester, Putnam, Rockland, Orange, Dutchess, and Sullivan. Established by the Judiciary Act of 1789, the office represents the United States government in criminal and civil cases across the country. The SDNY handles a broad array of cases, including but not limited to those involving white collar crime, domestic terrorism, cybercrime, public corruption, organized crime, and civil rights disputes.