The singer confirmed the news on social media.
"It's official, y'all!! Need you to root for me on #DWTS!!" she wrote. She also recorded a video message about her joining the show.
Khan, 62, is the seventh person to be announced for season 21 of the ABC dancing show. Bindi Irwin, Victor Espinoza, Nick Carter, Hayes Grier, Alexa and Carlos PenaVega were also announced as competitors this week.
"Dancing with the Stars" returns to ABC on Sept. 14.