Ruddy grew up on Long Island, New York, where his father was a police officer in Nassau County. He graduated from Chaminade High School in Mineola, NY before graduating summa cum laude with a degree in history from St. John's University in New York City in 1987. He then earned a master's degree in public policy from the London School of Economics and also studied at the Hebrew University of Jerusalem. He worked briefly as a high school teacher.

Early in his career, Ruddy was editor of an alternative media publication known as the New York Guardian. While with the Guardian, Ruddy gained notice for debunking a story in the PBS documentary Fighting on Two Fronts in World War II that an all-black army unit had liberated the Buchenwald and Dachau concentration camps. He called the documentary an example of "how the media can manipulate facts and narratives to create a revised history both believable and untrue." PBS subsequently withdrew its support for the documentary, following an independent investigation by the American Jewish Committee. Ruddy then moved into more mainstream journalism with the New York Post, which he joined as an investigative reporter late in the summer of 1993. After initially writing about abuse of Social Security disability benefits, he focused on the Vincent Foster case, the subject of an ongoing investigation after Foster had died earlier that year.

Since 1996, Ruddy has been Media Fellow at the Hoover Institution on War, Revolution and Peace at Stanford University. Ruddy serves on the Board of Directors of the Financial Publishers Association, an industry trade group representing the nation's financial media. Ruddy also served as a representative on the U.S. delegation headed by Senators Joseph Lieberman and Lindsey Graham to the NATO 44th Munich Security Conference.

In 2009, Ruddy was elected to the board of directors of the American Swiss Foundation, a non-profit organization that fosters relations between the two countries. The group represents Switzerland's leading banks, insurance and multinational corporations.

In January of 2010, Britain's Telegraph ranked Ruddy as one of the "100 Most Influential Conservatives" in the U.S. The paper said: "Chris Ruddy is an increasingly powerful and influential player in the conservative media and beyond."

Ruddy has been a "Sustaining Donor" to the Wikimedia Foundation.

Ruddy is one of (and perhaps the most prominent among) several individuals who have discussed questions regarding the death of White House counsel Vince Foster, work which was described by Former FBI Director William S. Sessions as "serious and compelling."

New York Post editor Eric Breindel recommended Ruddy for a job at the Pittsburgh Tribune-Review owned by Richard Mellon Scaife. In November 1994, Ruddy was hired to investigate the story full-time by the Tribune-Review. In between Ruddy's departure from the Post and joining the Tribune-Review, he put out a report through the Western Journalism Center criticizing the Fiske investigation as inadequate. With the help of Scaife, the Center took out full-page ads in major newspapers to promote the report (Scaife gave $330,000 to the Center in 1994-95 before ending his support).

Ruddy claimed that Park Police had staged the scene of Foster's death as described in their reports. One of the officers named by Ruddy sued him along with the Western Journalism Center, seeking $2 million in damages for libel. The suit was dismissed because Ruddy had said nothing libelous "of and concerning the officer".

Ruddy later built on his work on the Foster case for his book The Strange Death of Vincent Foster. In reviewing the book, Richard Brookhiser of the National Review called it "the St. Mark version of the gospel of the Foster cover-up: a plain narrative of the perceived failings of the official investigation, with minimal speculation." Shortly after the book came out, Fiske's successor as independent counsel, Kenneth Starr, released his report from the third investigation into Foster's death. Starr also concluded that Foster had committed suicide.

Ruddy followed up his book with an investigation of the circumstances surrounding Commerce Secretary Ron Brown's death. Brown had been killed in a plane crash in Croatia in 1996. Citing the opinion of a medical examiner who was involved in the investigation, but did not actually examine Brown's body, Ruddy raised the possibility that Brown had received a head wound from a gunshot. This notion was rejected by the medical examiner who did examine the corpse, who concluded that Brown died of blunt force injuries from the crash. An Air Force statement said there was no exit wound and explained that apparent "bullet fragments" were caused by defective x-ray film.

In 1998, impressed with the way news of the Lewinsky scandal circulated on the Internet, Ruddy decided to start an Internet news company. With financial support from Scaife and other investors, Ruddy founded Newsmax Media. The NewsMax.com website launched on September 16, 1998, with Ruddy serving as columnist and editor-in-chief. In addition to the web site, the company publishes a monthly magazine, also called Newsmax. After starting Newsmax, Ruddy was featured in a January 1999 Newsweek cover story as one of twenty "Stars of the New News."

In an October 2008 profile on Ruddy and Newsmax, The Palm Beach Post reported that Newsmax generates close to $25 million in revenues and is one of the most trafficked news websites in the U.S. In addition to its popular news portal, Newsmax.com, the company publishes Newsmax magazine and a host of health and financial newsletters.

A March 2009 profile of Ruddy and Newsmax on Forbes.com described his media company as the "great right hope" of the Republican Party and said after just a decade of operations it had become a "media powerhouse." Political analyst Dick Morris told Forbes that Newsmax had become the "most influential Republican-leaning media outlet" in the nation.

Dow Jones Marketwatch.com's media critic Jon Friedman noted that Ruddy had become a "bigger internet star than Rush Limbaugh" and that his web site ratings had surpassed that of the Drudgereport. Friedman suggested that Ruddy's success was due to a more balanced approach to news coverage and the GOP's worldview.

Folio magazine in its FOLIO 40 ranking identified Ruddy as a "C-Level Visionary" and notes that under his leadership Newsmax has flourished during the economic downturn "where success is really measured these days," continuing the Newsmax brand "ascendancy" both digitally and in print.

Though a conservative, Ruddy broke with the Bush Administration on the prosecution of the Iraq War, and was one of the first conservatives to do so. "I came out very strongly against the war in Iraq when it wasn't in vogue, back in 2004," Ruddy told The Palm Beach Post. "I lost some subscribers. But we are close to spending a trillion dollars on the war and there is no exit strategy," he added. "Lots of Republicans and conservatives are not that gung-ho on the war anymore and I think we broke the ice."

The paper noted that Ruddy, disenchanted by the war and runaway federal spending under Bush, re-evaluated the Clinton years and offered a kinder view of the administration he once criticized.

Compared with his reporting during Bill Clinton's presidency, Ruddy eventually took a more subdued view to Hillary Clinton's presidential campaign. He said she had moderated and no longer generated the same animosity among conservatives. Ruddy told The New York Times he and Scaife had changed their views: "Both of us have had a rethinking. Clinton wasn't such a bad president. In fact, he was a pretty good president in a lot of ways, and Dick feels that way today." This got some attention in conservative circles where Ruddy and Scaife were criticized for their new found liking of the former president. David Horowitz defended Ruddy in response, suggesting the comment referred to Clinton's domestic policies and arguing that Ruddy had not considered those objectionable even during the Clinton administration itself.

In the fall of 2007, Ruddy published a positive interview with former President Clinton on Newsmax.com, followed by a positive cover story in Newsmax magazine. The New York Times noted with reference to the event that politics had made "strange bedfellows".

Newsweek reported that Ruddy praised Clinton for his Foundation's global work, and explained that the interview, as well as a private lunch he and Scaife had had with Clinton (which Ruddy says was orchestrated by Ed Koch), were due to the shared view of himself and Scaife that Clinton was doing important work representing the U.S. globally while America was the target of criticism. He also said that he and Scaife had never suggested Clinton was involved in Foster's death, nor had they spread allegations about Bill Clinton's sex scandals, although their work may have encouraged others. Ruddy and Scaife again met Clinton for lunch at his office in September 2008. "We had a great time with him," Ruddy said of the meeting. He added, "We consider Bill Clinton a friend and he considers us friends." Forbes indicated the relationship between Ruddy and Clinton has continued and described them as "lunch chums."

A May 2009 New York Times Sunday magazine profile on the former president, "The Mellowing of William Jefferson Clinton," offered more details of the relationship between Ruddy and Clinton. The Arkansas Times said details about the friendship between Ruddy and Clinton in the New York Times profile was the "most amazing revelation" of their profile of the former president. Ruddy told the Times though he remained a "Reagan conservative," he had re-evaluated the Clinton presidency and suggested he had earned high marks as president for success in ending welfare, keeping government in check, and supporting free trade. Ruddy also noted that the Clinton Foundation was doing remarkable work globally.

In July 2010, it was reported that a group headed by Ruddy made a bid for Newsweek.Post/Newsweek executives say the Ruddy Group bid "was never taken seriously."