- Son of Canadian journalist Charles Jennings, got start in broadcasting at age 9 as the host of a Saturday-morning children's show on CBC Radio called Peter's People; his father disapproved because it smacked of nepotism.
- Dropped out of high school at 16 and went to work as a bank teller for the Royal Bank of Canada.
- Returned to Canadian broadcasting for good in the late 1950s, including a stint as the host of Club Thirteen, a dance show similar to American Bandstand, but also as a news anchor.
- Hired by ABC in 1964, and in 1965 became the anchor of Peter Jennings With the News, a 15-minute newscast that competed against—and lost to—Walter Cronkite on CBS, and Chet Huntley and David Brinkley on NBC.
- Left the anchor desk in 1967 to become a foreign correspondent, covering noteworthy events such as the 1972 Olympic Games in Munich, and in 1978 became the London anchor for ABC's World News Tonight.
- Succeeded the late Frank Reynolds as sole anchor (and senior editor) of World News Tonight, a position he would hold—and be known as one of the Big 3, with NBC's Tom Brokaw and CBS' Dan Rather—until his final broadcast on April 5, 2005, when he announced he had lung cancer.
- Became a U.S. citizen on May 2003, but also retained his Canadian citizenship.
- With Todd Brewster, coauthor of several books, including The Century (1998) and In Search of America (2002).
- Kati Marton — Ex-wife
- Kayce Freed Jennings — Wife
- Sarah Jennings — Sister
- Valerie Godsoe — Ex-wife
- Anouchka "Annie" Malouf — Ex-wife
- Elizabeth Jennings — Daughter
- Christopher Jennings — Son
- Charles Jennings — Father
- Elizabeth Osborne Jennings — Mother