The Post-Gazette began its history as a four-page weekly called The Pittsburgh Gazette, first published on July 29, 1786, with the encouragement of Hugh Henry Brackenridge.

[5] In 1820, under publishers Eichbaum and Johnston and editor Morgan Neville, the name changed to Pittsburgh Gazette and Manufacturing and Mercantile Advertiser.

Craig turned the Gazette into the city's first daily paper, issued every afternoon except Sunday starting on July 30, 1833.

[10] By the 1850s the Gazette was credited with helping to organize a local chapter of the new Republican Party, and with contributing to the election of Abraham Lincoln.

After swapping the Sun in return for Hearst's Gazette Times, Block had both morning papers, which he combined to form the Post-Gazette.

[20] In November 1961, the Post-Gazette entered into an agreement with the Pittsburgh Press Company to combine their production and advertising sales operations.

[22] The agreement gave the Post-Gazette a new home in the Press building, a comfortable upgrade from the hated "Sun-Telly barn".

While maintaining the original paper in its facilities in Greensburg, he expanded it with a new Pittsburgh edition to serve the city and its suburbs.

Relations between the Post-Gazette and Tribune-Review, during its existence as a local print publication, were often competitive and frequently hostile, given Scaife's longstanding distaste for what he considered the Blocks' liberalism.

[37] First Niagara Bank, which had entered the Pittsburgh market the year before after acquiring National City branches from Pittsburgh-based PNC Financial Services,[38] took over the naming rights to the facility and is now known as the KeyBank Pavilion.

In 1957, the Post-Gazette partnered with the H. Kenneth Brennen family, local radio owners, to launch WIIC-TV (now WPXI) as the area's first full-time NBC affiliate.

In 2019, the Pittsburgh Post-Gazette was a founding member of Spotlight PA, an investigative reporting partnership focused on Pennsylvania.

[50] The firing came in the context of increasing support for President Donald Trump and political conservatism on the Post-Gazette editorial page.

[50] The Association of American Editorial Cartoonists said in a statement: "It's as simple as this: Rogers was fired for refusing to do cartoons extolling Trump.

[50] Rogers wrote in the New York Times that the paper's new management had decided, in the lead-up to his firing, that his cartoons satirizing Trump "were 'too angry.

[50] As a freelancer, Rogers was named as a finalist for the 2019 Pulitzer Prize in editorial cartooning, with the committee citing his "provocative illustrations that channeled cultural and historical references with expert artistry and an eye for hypocrisy and injustice.

[55] The Post-Gazette said that Johnson, an African American, had shown bias by making a tweet that highlighted extensive littering from a Kenny Chesney concert tailgate.

In 1938, Ray Sprigle won the Pulitzer Prize for Reporting for his investigation revealing that newly appointed Supreme Court Justice Hugo Black had been a member of the Ku Klux Klan.

Photographer John Kaplan won the 1992 Pulitzer Prize for Feature Photography for a series of photo essays on 21-year-olds, which was published in the Post-Gazette and two other papers of the Block Newspapers group.

[58] The Post-Gazette won the 2019 Pulitzer Prize for Breaking News Reporting for its coverage of the Pittsburgh synagogue shooting.

"[59] In 1997, Bill Moushey won the National Press Club’s Freedom of Information Award on a series investigating the Federal Witness Protection Program and was a finalist for the Pulitzer.

[62] Smith, Stephanie Strasburg, and Shelly Bradbury were finalists for the 2020 Pulitzer Prize for Local Reporting for an investigation into sexual abuse in Pennsylvania's Amish and Mennonite communities.