Brnovich earned her Bachelor of Business Administration, Master of Science, and Juris Doctor from the University of Wisconsin–Madison.

[2] Brnovich began her legal career serving as a prosecutor with the Maricopa County Attorney's Office.

[3] In 2003, she became a commissioner on the Maricopa County Superior Court, where she presided over numerous criminal jury trials over the next five years.

Brnovich was appointed by Governor of Arizona Janet Napolitano as a trial court judge in January 2009 and was retained by voters in both 2012 and 2016.

She was nominated to the seat vacated by Judge Neil V. Wake, who assumed senior status on July 5, 2016.