Jen Stewart served as chief of staff to former Secretary of Defense Mark T. Esper from January 2020 until November 2020. Prior to this role, she served as the Republican staff director for the House Armed Services Committee and as a senior adviser to former chairman of the Joint Chiefs of Staff General Joseph F. Dunford. In November 2020, Stewart, along with several other senior civilian personnel at the Department of Defense, resigned a day after President Donald Trump fired Secretary Esper.
In approximately July 2021, Jen Stewart joined WestExec Advisors, a strategic advisory firm co-founded by former under secretary of defense for policy Michèle Flournoy and Secretary of State Antony Blinken, as a senior advisor. WestExec Advisors brands itself as a “bipartisan team of senior national security leaders with the most recent experience … in defense, foreign policy, intelligence, economics, cybersecurity, data privacy, and strategic communications.” In late 2020, Blinken and Avril Haines, who was later confirmed as the Director of National Intelligence disclosed that clients they had advised through WestExec included defense contractors Boeing, McKinsey & Company, and Palantir.
According to her company profile, “she has nineteen years of public service, including over fifteen consecutive years of serving in senior national security positions at both the Department of Defense and in Congress.” She is also listed as the firm's senior vice president.