Kim and her husband Jang Sung-taek are Kim Jong-un's closest advisers. They were chosen by his late father Kim Jong-il.
They are thought to be building the son's military reputation amid suspicions that some North Korean generals do not trust him.
Kim Jong-un is drawing worldwide attention for his belligerent approach in carrying out nuclear tests, despite global concern.
Tensions have been heightened on the Korean Peninsula since North Korea conducted its third nuclear test February 12 in protest against joint military drills between South Korea and the US.