President and COO Chris Kubasik will succeed Stevens next January.
Stevens, 60, will remain chairman through January 2014, contingent upon approval by the board and election by shareholders.
"Bob Stevens has had an extraordinarily distinguished career, working tirelessly on behalf of Lockheed Martin's customers, shareholders and employees by applying his full-spectrum leadership to build a strategically focused company with a portfolio shaped to meet the challenges of today's global security environment," said Douglas McCorkindale, Lockheed Martin's lead director.
"Throughout his tenure, Bob and the board have focused on developing talent and assuring a high-quality succession plan as a cornerstone of good corporate governance. As a result, incredibly talented leaders like Chris and Marillyn are ready to assume greater responsibilities."
President and COO Chris Kubasik, 51, will succeed Stevens as CEO effective Jan. 1, 2013, according to Bethesda, Md.-based Lockheed Martin.
Coinciding with the moves, the board elected Marillyn Hewson, 58, to succeed Kubasik as president and COO, effective Jan. 1, 2013.
Hewson's successor as executive vice president of Lockheed Martin's Electronic Systems business area will be announced later this year, the company noted.
"Chris and Marillyn are superbly well prepared to guide the continuous evolution of Lockheed Martin's strategies and operating concepts in ways that will allow us to simultaneously address the evolving needs of customers and the expectations of shareholders," Stevens said.
Kubasik has served as president and COO since January 2010, and has served with Stevens in the executive office of the chairman since October 2011.
He previously was executive vice president of the Electronic Systems business area and, earlier, the company's chief financial officer.
Hewson was named executive vice president of the Electronic Systems business area in January 2010.
In her 29-year career at Lockheed Martin, she has held leadership positions on the corporate staff and in three of the corporation's four businesses.
After serving as chief financial officer, Stevens was named president in 2000, and became CEO in 2004.
Stevens serves on the international advisory boards of the Atlantic Council and the British-American Business Council and is on the executive committee of the Aerospace Industries Association board of governors.
Stevens, a U.S. Marine Corps veteran, is a member of the Council on Foreign Relations, lead director of the Monsanto Company, and a member of the board of directors of the Congressional Medal of Honor Foundation.