Born in Glasgow, Kentucky, Diane Sawyer is the daughter of Jean W. Sawyer – an elementary school teacher – and Erbon Powers "Tom" Sawyer, a judge. Soon after her birth, her family moved to Louisville, Kentucky, where her father rose to local prominence as a Republican politician and community leader; he was Kentucky's Jefferson County Judge/Executive when he was killed in a car accident on Louisville's Interstate 64 in 1969. E. P. "Tom" Sawyer State Park, located in the Frey's Hill area of Louisville, is named in his honor.
Sawyer attended Seneca High School in the Buechel area of Louisville. In 1963, she won the "America's Junior Miss" scholarship pageant as a representative from the State of Kentucky.
During the period from 1962–1965, Sawyer was "America's Junior Miss" touring the country to promote the Coca-Cola Pavilion at the 1964-1965 New York World's Fair.
In 1967, she received a bachelor of arts degree with a major in English from Wellesley College in Wellesley, Massachusetts. There, she was a member of the Wellesley College Blue Notes, an A Capella group and Phi Sigma Lecture Society. She attended one semester of law school at the University of Louisville before turning to journalism.
Sawyer began her professional career in Republican Party politics. In 1970, White House Press Secretary Ron Ziegler hired her to serve in the administration of U.S. President Richard Nixon. Sawyer continued through Nixon's resignation from the presidency in 1974 and worked on the Nixon-Ford transition team in 1974–1975, after which she decamped with Nixon to California and helped him write his memoirs, published in 1978. She also helped prepare Nixon for his famous set of television interviews with journalist David Frost in 1977.
Years later, Sawyer would be suspected of being Deep Throat, the source of leaks of classified information to journalist Bob Woodward during the Watergate scandal. In 2005 Deep Throat was identified as W. Mark Felt, but prior to that, Rabbi Baruch Korff – a longtime Nixon confidant and defender known as "Nixon's rabbi" – said on his deathbed that he believed Sawyer was Deep Throat. Sawyer laughed it off, and she was one of six people to request and receive a public denial from Woodward.
In 1978, Sawyer joined CBS News as a political correspondent and became a co-anchor, with Bill Kurtis, of the CBS Morning News in 1981. In 1984, she became a correspondent for 60 Minutes, a CBS News investigative television newsmagazine; she remained for five years.
In 1989, she moved to ABC News to co-anchor newsmagazine Primetime Live, with Sam Donaldson. From 1998 to 2000, she would become a co-anchor for ABC's 20/20, also a newsmagazine, co-anchoring on Wednesdays with Donaldson and on Sundays with Barbara Walters.
In 1999, Sawyer returned to morning news (GMA) as the co-anchor of GMA with Charles Gibson. The assignment was putatively temporary, but her success in the position, measured by a close in the gap with front-runner Today, NBC News's morning program, sustained her in the position far longer than anticipated. The GMA program has never regained the lost viewers, nor beaten its early morning competition since Joan Lunden retired after 17 years as co-host in 1997. On September 2, 2009, she was announced as the successor to Gibson, who retired as ABC World News anchor on Friday, December 18, 2009. She left GMA on December 11, 2009, and was scheduled to become the ABC World News anchor in January 2010. However, on December 1, 2009, The New York Times reported that instead of moving to ABC World News in January 2010, Sawyer would start on December 21, 2009, three days after Gibson's departure . For over a year in 2010-2011 with Katie Couric then anchor of CBS News, two of the three network news anchors on broadcast television were women. Ratings jumped 8% for 60 days after her first four weeks, averaging 8.8 million viewers. She signs off at the end of her nightly broadcast with "I'll see you right back here tomorrow night." The show, like its competitor evening newscasts, ended the year with ratings 14% below that of the preceding year.