Ann B. Jorgensen was born in 1955 in Troy, New York. She graduated from Loyola University of Chicago and earned her Juris Doctor from DePaul University College of Law in 1980. She served as an Assistant State's Attorney in DuPage County until entering the private practice of law in the Law Offices of John F. Donahue (now known as Donahue, Sowa & Magana), where her practice concentrated in criminal defense and administrative hearings.

Judge Jorgensen was appointed as an Associate Judge for the 18th Judicial Circuit in 1989. She was assigned to the Law Division and thereafter appointed Supervising Judge of the Mandatory Arbitration Program. In 1994, Judge Jorgensen was elected Circuit Judge and subsequently retained in 2000 and 2006. As a Circuit Judge, she served as the Presiding Judge of the Felony Division and the DuPage County Drug Court. In 2005, her fellow circuit judges elected her as Chief Judge of the 18th Judicial Circuit, where she served until her appointment to the Appellate Court in July of 2008.

Judge Jorgensen is a Past President of the Illinois Judges Association, current member of its Board of Directors and of the Illinois Judges Association Foundation. She is also an active member of the Illinois State Bar Association, DuPage County Bar Association and DuPage Association of Women Lawyers. She has served on numerous Supreme Court committees and is currently a member of the Special Supreme Court Committee to Study Courtroom and Judicial Security.

She and her husband, Dr. Richard Jorgensen, have two grown children.