The seven-time Emmy Award winner is to play a retired, high-powered business executive and the mother of Brooke Shields' character Wendy.
Moore's first appearance on the series will be in the show's Season 2 premiere Sept. 24, NBC said.
"I'm fortunate to have had a front row seat to the evolution of working women on television," Moore said in a statement. "It's been great fun to watch the strong female characters of 'Lipstick Jungle' go at it week after week. I absolutely adore Brooke and I'm delighted to be a part of a show which is so well written."
"I am excited and extremely honored to have an actress of Mary Tyler Moore's stature and talent join our show," Shields added.