Brokaw was born in Webster, South Dakota He was the eldest of their three sons and was named after his maternal great-grandfather, Thomas Conley. The Brokaws lived for short periods in Bristol, Igloo, and Pickstown, before settling in Yankton, where Brokaw attended high school.

Brokaw's television career began at KTIV in Sioux City, Iowa followed by stints at KMTV-TV in Omaha, Nebraska, and WSB-TV in Atlanta, Georgia, In 1966, he joined NBC News, reporting from California and anchoring the 11 p.m. news for KNBC-TV in Los Angeles. In 1973, NBC made Brokaw White House correspondent, covering the Watergate scandal, and anchor of the Saturday editions of Nightly News. He became host of NBC's Today Show in 1976 and remained in the job until 1981. On April 5, 1982, Brokaw began co-anchoring NBC Nightly News from New York with Roger Mudd.

During his tenure, Brokaw reported on the live opening of the Berlin Wall, conducted a historic 1987 interview with Mikhail Gorbachev and "awarded" the 2000 election to Al Gore before retracting the following morning. Brokaw postponed his retirement in order to cover the September 11, 2001, terrorist attacks against the United States. He retired from NBC Nightly News in 2004 and was replaced by Brian Williams. Brokaw has kept busy during his retirement, hosting History Channel documentaries, delivering speeches and eulogies, and serving on the board of directors for several organizations, among other roles. Brokaw returned to the NBC anchor desk on June 13, 2008, to announce the tragic death of friend and colleague Tim Russert. Brokaw would act as interim host for Russert's successful Sunday morning series, Meet the Press, until a suitable replacement could be found. He also hosted the second presidential debate between Barack Obama and John McCain on October 7, 2008, in Nashville, Tennessee.

In addition to his historic reign in the anchor seat, Tom Brokaw is known for producing many specials for NBC, including 2001's "The Greatest Generation Speaks," based on Brokaw's best-selling 1998 book, The Greatest Generation. In February 2014, a 74-year-old Brokaw announced that he'd been diagnosed with multiple myeloma, a cancer affected the blood cells in bone marrow, in August 2013. According to NBC News, doctors remain optimistic about Brokaw's outlook and treatment. "With the exceptional support of my family, medical team and friends, I am very optimistic about the future and look forward to continuing my life, my work and adventures still to come. I remain the luckiest guy I know," the longtime TV journalist said in a statement, adding, "I am very grateful for the interest in my condition, but I also hope everyone understands I wish to keep this a private matter."

Brokaw and wife Meredith Lynn Auld have been married since 1962. The couple has three daughters, Jennifer, Andrea and Sarah.