Hewson joined Lockheed Martin in 1982. She has held a variety of increasingly responsible executive positions with the company, including President and Chief Operating Officer, and Executive Vice President of Lockheed Martin’s Electronic Systems business area. On November 9, 2012 she was elected to Lockheed Martin’s Board of Directors. She has been the CEO since January 2013. She also serves on the Board of directors for Sandia National Laboratories and DuPont.
In 2010, 2011, and 2012 she was named by Fortune magazine as one of the "50 Most Powerful Women in Business".