O’Connor's career centered around state government until she was nominated to the U.S. Supreme Court in 1981. Before that, she served in various capacities, including Arizona state senator. O’Connor earned a reputation as hard working, fair, tough, and thoughtful. She was in favor of the death penalty, limited government spending, and access to abortion. She was the first woman to serve as a state senate majority leader in the United States.

In 1974, O’Connor ran for Superior Court judge of Arizona's Maricopa County and won. Five years later, she was appointed to the state court of appeals. In this position, she gained national attention by expressing her judicial philosophy: If state courts have already given a matter full and fair treatment, federal judges should refuse to intervene or hear appeals. She published her thoughts in an article in the Summer 1981 issue of William and Mary Law Review. The article communicated clearly O’Connor's belief in states’ rights.

O’Connor was the first woman to sit on the Supreme Court. President Ronald Reagan (1911–2004; served 1981–89) chose her because of her mostly conservative views and her ability to gain public and congressional support. At first, feminists supported her for what they believed were her pro-women stances on various issues. But by her second year on the Court, feminists were not as supportive of O’Connor. Although she refused to support the prohibition of abortions, she did uphold a series of laws curbing women's access to legal abortion.

O’Connor retired in 2006 after serving twenty-four years as a Supreme Court judge. Later that year, she was listed among “America's Best Leaders” by U.S. News & World Report and the Center for Public Leadership at Harvard University's John F. Kennedy School of Government.