Mary Lane Mikva graduated from the Northwestern University Pritzker School of Law, cum laude, in 1980. After graduation, she was a law clerk to Associate Justice William J. Brennan, Jr., of the United States Supreme Court and to Judge Prentice Marshall of the Northern District of Illinois. As an attorney, she practiced criminal defense and employment law. She worked in private practice and also for the City of Chicago.

Justice Mikva was elected to the Circuit Court of Cook County in November of 2004. She served for six years in the Child Protection Division, where she helped develop programs and materials for encouraging teenagers in foster care to delay pregnancy. She then served for six years in the Chancery Division where she remained involved in judicial training and education on a variety of subjects. She was appointed to the First District Appellate Court in July of 2016.

Justice Mikva is an avid cyclist who commutes to work by bicycle through Chicago winters. She is married to Steven Cohen and has two children, Rebecca and Jordan.