@11112011 Abercrombie-Winstanley joined the United States Foreign Service in 1985 and was posted to Baghdad, Iraq. She then went on to serve at the U.S. embassies in Jakarta, Indonesia and Cairo, Egypt. She returned stateside to become a Special Assistant for Middle Eastern and African Affairs to Deputy Assistant Secretary of State Lawrence Eagleburger (1991–1993). After a year of intensive Arabic language training in Tunisia, Abercrombie-Winstanley then became a political officer at the U.S. Embassy in Tel Aviv, Israel (1994–97), focusing on Israel–Palestine relations.[3] from 1997 to 1998 she was assigned to the Senate Foreign Relations Committee.

From 1998 to 2000, she served in roles with the United States National Security Council, serving as director for the Arabian Peninsula with the Near East South Asia Center and later as director of legislative affairs.

Abercrombie-Winstanley served as consul general in Jeddah, Saudi Arabia[4] from 2002 to 2005. She was the first female consul general in that location.[5] While there, she survived an al-Qaeda attack on the consulate on December 6, 2004, and was cited "for acts of courage" during the attack.[6] From 2005 to 2006, she served as director of Middle East Area studies in the Foreign Service Institute, and then spent two years as director for Egypt, Syria, Lebanon and Jordan at the Bureau of Near Eastern Affairs. From 2008 to 2012, she was deputy coordinator for counterterrorism.

In 2012, President Barack Obama nominated her to become U.S. ambassador to Malta.[6] She served in that role from May 2, 2012, to January 13, 2016.

Abercrombie-Winstanley was sworn in April 12, 2021 to serve under Secretary Antony Blinken as chief diversity and inclusion officer for the United States Department of State.[