During 2002 and 2003, Prelogar studied creative writing at the University of St Andrews as a Robert T. Jones Scholar, receiving an M.Litt.

She then entered private practice as an associate at Hogan Lovells in Washington, D.C. She taught a course at Harvard Law School on Supreme Court and appellate advocacy.

[21] She also performed in a mock trial with Brett Kavanaugh and Ketanji Brown Jackson in 2016 prior to their appointments to the Supreme Court.

She was briefly detailed to the Mueller special counsel investigation into Russian interference in the 2016 United States presidential election.

[27] She was prevented from serving while the nomination was before the Senate as a result of the terms of the Federal Vacancies Reform Act of 1998.

[28] On October 28, 2021, the Senate confirmed Prelogar as solicitor general by a vote of 53–36,[29] making her the second woman to hold the position after Elena Kagan, who later became a Supreme Court Justice.