Born in New York City on September 10, 1949, O’Reilly spent most of his childhood on Long Island. He attended Marist College in New Jersey, where he majored in history. After a stint teaching history and English at a Catholic high school, O’Reilly returned to school, getting a Master of Arts in broadcast journalism from Boston University and a Master of Public Administration from Harvard University. While in graduate school, he worked as a reporter and opinion columnist for a series of newspapers. By 1973, O’Reilly had started working as a news anchor, weatherman, and reporter for a series of local television stations in Texas, Pennsylvania, New Jersey, and New York. He then worked for CBS News and ABC News as a reporter, a news correspondent, and a show host. From 1989 to 1994, O’Reilly was a host on the tabloid news show Inside Edition. In 1998, he wrote and published a novel, the thriller Those Who Trespass.

O’Reilly became one of the first hosts on FOX News, helming The O’Reilly Factor, a conservative news show. He was criticized by organizations such as Media Matters for misinformation, while at the same time, he was also a frequent guest on the progressive news parody show, The Daily Show, hosted by Jon Stewart. In interviews, O’Reilly himself identifies as a political independent. He was fired from FOX News in 2017 after The New York Times reported that he had settled five sexual harassment lawsuits during his time at FOX News involving allegations he still disputes. Since then, O’Reilly has hosted the radio shows The Radio Factor and Common Sense with Bill O’Reilly and has been a writer and television producer, being involved with National Geographic television adaptations of his and Martin Dugard’s books Killing Lincoln, Killing Reagan, Killing Jesus, and Killing Kennedy.