They will hold their wedding on Oct. 12 at a Seoul hotel, according to Lee's Bonboo Entertainment and Kangnam's Dmost Entertainment.
They first met on SBS' reality show "Law of the Jungle" in September last year and became a couple. They confirmed their relationship in March.
Lee, 30, is the most successful athlete in South Korean speed skating. She won the gold medal in the women's 500 meters at the 2010 Vancouver Winter Olympics and at Sochi four years later. She took the silver in the same event at 2018 PyeongChang. She announced her retirement in May.
Kangnam, who has a Japanese father and a Korean mother, started his entertainment career with hip hop band MIB in 2011.
The 32-year old Japan-born singer, who is preparing for Korean naturalization, said he proposed marriage to Lee months ago and she accepted. (Yonhap)