The Irish Times is launched at 4 Lower Abbey Street in Dublin on March 29, 1859. The first appearance of a newspaper using the name occurs in 1823 but it closes in 1825. The title is revived as a thrice weekly publication by Major Lawrence E. Knox. It is originally founded as a moderate Protestant newspaper, reflecting the politics of Knox, who stands unsuccessfully as a parliamentary candidate for Isaac Butt’s Home Rule League. In its early days, its main competitor is the Dublin Daily Express.

After Knox’s death in 1873, the paper is sold to the widow of Sir John Arnott, MP, a former Lord Mayor of Cork and owner of Arnotts, one of Dublin’s major department stores. The sale, for £35,000, leads to two major changes. Its headquarters is shifted to 31 Westmoreland Street, remaining in buildings on or near that site until 2005. Its politics also shifts dramatically, becoming predominantly Unionist in outlook, and it is closely associated with the Irish Unionist Alliance. The paper, along with the Irish Independent and various regional papers, calls for the execution of the leaders of the failed 1916 Easter Rising.

Though the paper becomes a publicly listed company in 1900, the family continues to hold a majority shareholding until the 1960s. The last member of the Arnott family to sit on the paper’s board is Sir Lauriston Arnott, who dies in 1958.

The editor during the 1930s, R. M. “Bertie” Smyllie, has strong anti-fascist views: he angers the Irish Catholic hierarchy by opposing General Francisco Franco during the Spanish Civil War. Later, The Irish Times, like other national newspapers, has problems with Irish Government censorship during World War II. The newspaper is largely pro-Allied and is opposed to the Éamon de Valera government’s policy of neutrality.

In 1974, ownership is transferred to a non-charitable trust, The Irish Times Trust. The Trust is set up as “a company limited by guarantee” to purchase The Irish Times Limited and to ensure that The Irish Times will be published as an independent newspaper with specific editorial objectives. The former owner, Major Thomas Bleakley McDowell, is made “president for life” of the trust which runs the paper and is paid a large dividend. However several years later the articles of the Trust are adjusted, giving Major McDowell ten preference shares and one more vote than the combined votes of all the other directors should any move be made to remove him. Major McDowell dies in 2009.

The Trust is regulated by a legal document, the Memorandum and Articles of Association, and controlled by a maximum of eleven Governors under company law. It is not a charity and does not have charitable status. It has no beneficial shareholders and it cannot pay dividends. Any profits made by The Irish Times cannot be distributed to the Trust but must be used to strengthen the newspaper, directly or indirectly.

In 1994, The Irish Times establishes a website called Irish-times.ie, the first newspaper in Ireland and one of the first 30 newspapers in the world to do so. The company acquires the domain name Ireland.com in 1997, and from 1999 to 2008, uses it to publish its online edition. On June 30, 2008, the company relaunches Ireland.com as a separate lifestyle portal and the online edition of the newspaper is now published at irishtimes.com. It is supplied free of charge, but a subscription is charged to view its archives.

On October 15, 2012, John O’Shea, Head of Online, The Irish Times, announces that the ireland.com domain name has been sold to Tourism Ireland, and that the ireland.com email service will end on November 7, 2012, affecting about 15,000 subscribers. The newspaper announces on February 17, 2015 the reintroduction of a paywall for its website, irishtimes.com, beginning on February 23.

In December 2017, it is reported that The Irish Times has reached an agreement to purchase the newspaper, radio and website interests of Landmark Media Investments which include the Irish Examiner. Initially subject to regulatory approval, this sale is completed in July 2018. In September 2018, following the Landmark Media Investments acquisition, The Irish Times starts a voluntary redundancy scheme.

Average print circulation is approximately 100,000 copies per issue in 2011, dropping to approximately 62,000 by 2017. The circulation of the newspaper is no longer audited.