Mearsheimer was born in December 1947 in Brooklyn, New York. He was raised in New York City until the age of eight, when his parents moved his family to Croton-on-Hudson, New York, a suburb located in Westchester County.

When he was 17, Mearsheimer enlisted in the U.S. Army. After one year as an enlisted member, he chose to attend the United States Military Academy at West Point. He attended West Point from 1966-1970. After graduation, he served for five years as an officer in the U.S. Air Force.

While in the Air Force, Mearsheimer earned a Masters Degree in International Relations from the University of Southern California in 1974. He subsequently entered Cornell University and earned a Ph.D. in government, specifically in international relations, in 1981. From 1978-1979, was a research fellow at the Brookings Institution in Washington, D.C. From 1980-1982, he was a post-doctoral fellow at Harvard University’s Center for International Affairs. During the 1998-1999 academic year, he was the Whitney H. Shepardson Fellow at the Council on Foreign Relations in New York.

Since 1982, Mearsheimer has been a member of the faculty of the Department of Political Science at the University of Chicago. He became an associate professor in 1984, a full professor in 1987, and was appointed the R. Wendell Harrison Distinguished Service Professor in 1996. From 1989-1992, he served as chairman of the department. He also holds a position as a faculty member in the Committee on International Relations graduate program, and is the co-director of the Program on International Security Policy.

Mearsheimer has written extensively about national security policy and international relations theory, especially realism, which he defines as a state’s tendency to attempt to gain as much relative power as possible and eventually become the hegemon of the international system.

Mearsheimer’s books include Conventional Deterrence (1983), which won the Edgar S. Furniss Jr., Book Award, Nuclear Deterrence: Ethics and Strategy (1985), Liddell Hart and the Weight of History (1988), and The Tragedy of Great Power Politics (2001), which won the Joseph Lepgold Book Prize, and The Israel Lobby and U.S. Foreign Policy (2007). He has also written many articles that have appeared in academic journals like International Security, and popular magazines like The London Review of Books. Furthermore he has written a number of op-ed pieces for the New York Times, the Los Angeles Times, and the Chicago Tribune.

Mearsheimer has won a number of teaching awards. He received the Clark Award for Distinguished Teaching when he was a graduate student at Cornell in 1977, and he won the Quantrell Award for Excellence in Undergraduate Teaching at the University of Chicago in 1985. In addition, he was selected as a Phi Beta Kappa Visiting Scholar for the 1993-1994 academic year. In that capacity, he gave a series of talks at eight colleges and universities. In 2003, he was elected to the American Academy of Arts and Sciences.

Mearsheimer has acquired some renown among the University of Chicago community for his colorful language and idiomatic speech in his classes and lectures. He famously refers to the United States as "Uncle Sugar," the Soviet Union as "the Bear;" the action of international politics occurs "all over God's little green acre."

In March 2006, Mearsheimer and Stephen Walt, academic dean and professor of International Relations at the Harvard Kennedy School of Government, published a working paper and an article in the London Review of Books discussing the power of the Israel lobby in shaping US foreign policy. They define the Israel lobby as "a loose coalition of individuals and organizations who actively work to steer US foreign policy in a pro-Israel direction." They emphasize that it is not appropriate to label it a "Jewish lobby", because not all Jews feel a strong attachment to Israel and because some of the individuals and groups who work to foster U.S. support for Israel are not Jewish; according to Mearsheimer and Walt, Christian Zionists play an important role. Finally, they emphasize that the lobby is not a cabal or a conspiracy but simply a powerful interest group like the NRA or the farm lobby. Their core argument is that the policies that the lobby pushes are not in the US' national interest, nor ultimately that of Israel. Those pieces generated extensive media coverage, and led to a wide-ranging and often polemic debate between supporters and opponents of their argument.

Mearsheimer and Walt subsequently turned the article into a book – The Israel Lobby and US Foreign Policy – which was published in late August 2007. The book has been translated into seventeen languages and published in twenty-one countries. While the book received many favorable reviews outside the United States, it did not receive any positive reviews in the American mainstream media.[citation needed] Some of the most positive reviews came from Israel. Mearsheimer and Walt traveled extensively throughout the United States to talk about the book. They also traveled to Canada, Europe and the Middle East.