Evans was born in Kingsville, Texas, the son of college professor, author and Atomic Energy Commission official Medford B. Evans and classics scholar Josephine Stanton Evans. He grew up in Chattanooga, Tennessee and the Washington, D.C. metropolitan area. Evans graduated magna cum laude from Yale University, Phi Beta Kappa, in 1955, with a B.A. in English, followed by graduate work in economics at New York University under Ludwig von Mises. He has been awarded honorary doctorates from Syracuse University, John Marshall Law School, Grove City College and Francisco Marroquín University.

Upon graduating from Yale, where he had been an editor for the Yale Daily News, Evans entered the field of professional journalism. As an undergraduate, he had read One Is a Crowd by Frank Chodorov. In The Conservative Intellectual Movement in America Since 1945, George H. Nash writes:

In 1955, Evans became assistant editor of The Freeman, where Chodorov was editor. The following year, he joined the staff of William F. Buckley's fledgling National Review (where he served as associate editor from 1960 to 1973) and became managing editor of Human Events, where he is currently a contributing editor. He became a proponent of National Review co-editor Frank Meyer's "fusionism," a political philosophy reconciling the traditionalist and libertarian tendencies of the conservative movement. Evans argued that freedom and virtue are not antagonistic, but complementary:

In 1959, Evans became head editorial writer of The Indianapolis News, rising to editor the following year—at 26, the nation's youngest editor of a metropolitan daily newspaper—a position he held until 1974. In 1959 and 1960, he won the Freedom Foundation award for editorial writing, and in 1960, the National Headliners Club Award for “consistently outstanding editorial pages.” In 1971, Evans became a commentator for the CBS Television and Radio Networks, and in 1980 became a commentator for National Public Radio, the Voice of America, Radio America and WGMS-FM in Washington, D.C. In 1974, he became a nationally syndicated columnist for the Los Angeles Times syndicate. Barry Goldwater wrote that Evans "writes with the strength and conviction and authority of experience." In a 1975 radio address, Ronald Reagan cited Evans as "a very fine journalist." In 1977, Evans founded the National Journalism Center, where he served as director until 2002. In 1980, he became an adjunct professor of journalism at Troy University in Troy, Alabama, where he currently holds the Buchanan Chair of Journalism. In 1981-2002, he was publisher of Consumers' Research magazine. In 2009, Accuracy in Media awarded Evans the Reed Irvine lifetime achievement Award for Investigative Journalism. Evans expressed his journalistic philosophy as follows:

Evans was present at Great Elm, the family home of William F. Buckley in Sharon, Connecticut, at the founding of Young Americans for Freedom, where on September 11, 1960, he wrote YAF's charter, the Sharon Statement. Some conservatives still revere this document as a concise statement of their principles.

In 1971-1977, Evans served as chairman of the American Conservative Union (ACU). He was one of the first conservatives to denounce Richard Nixon, just a year into his first term and long before Watergate, co-writing a January 1970 ACU report concluding that "conservatives get the words; the liberals get all the action." Under Evans' leadership, the ACU issued a July 1971 statement recounting Nixon's record, concluding, “the American Conservative Union has resolved to suspend our support of the Administration.” In June 1975, ACU called upon Ronald Reagan to challenge incumbent Gerald Ford for the 1976 Republican presidential nomination. In June 1982, Evans and others met with President Reagan, warning him about White House staff who thought they could make a deal with the Democratic Congress. (Reagan subsequently made such a deal, in which for each $1 in higher taxes Congress promised $3 in spending cuts; Reagan delivered the tax hike, but Congress reneged, actually increasing spending.)

In 1974, Evans founded the Education and Research Institute, of which he is still chairman. He has also served as president of The Philadelphia Society; a member of the Council for National Policy and Young Americans for Freedom National Advisory Board; and a trustee of the Intercollegiate Studies Institute (ISI), and is a member of the Board of Advisors of the National Tax Limitation Committee. Evans has also been an effective plaintiff in numerous Federal Court cases involving the First Amendment issue of "freedom of information." He is the winner of the Ashbrook Center for Public Affairs' John M. Ashbrook Award and four Freedoms Foundation George Washington medals. The ISI's M. Stanton Evans Alumni Award is named in his honor.