Hewson, who became the first female chief executive at Lockheed in January 2013, will assume the top spot on the board with the retirement of current chairman Robert Stevens.
Headquartered in Bethesda, Maryland, Lockheed employs about 116,000 people worldwide. The company's 2012 net sales came in at USD 47.2 billion.
Hewson's appointment is the latest in a series of high-profile leadership posts for women.
Last week, General Motors became the first major auto company to appoint a female chief executive, Mary Barra.