Myers was born to an Irish emigrant family in Leicester, England, where his father was a General Practitioner. He attended Ratcliffe College, a Roman Catholic independent school.

Myers was accepted by University College Dublin, where he subsequently obtained a degree in History in 1969. He began to work as a journalist for RTÉ, and reported from Northern Ireland during the height of the Troubles from 1971 to 1978. In the 1980s, he covered the Lebanese Civil War, and in the 1990s the Bosnian War. Otherwise he has been based in Dublin and Liverpool.

Myers is married and lives in Barretstown, Ballymore Eustace, County Kildare.

Myers' Irish Times opinion columns were often in contrast to its editorial position, which led to some conflict with his editors. In early January 2005, The Irish Times refused to publish a column in which he accused the Provisional Irish Republican Army (IRA) of responsibility for the Northern Bank robbery. It was later published by the Daily Telegraph He often advocates support for the United States, though he is sometimes critical of the foreign policies of the Bush administration. He ultimately endorsed the 2003 invasion of Iraq. He has praised George W. Bush, but has also described him as 'mad'. He is frequently critical of anti-war activists.

Myers is sceptical of the viability of multiculturalism and favours limits on immigration to prevent the growth of racial tension in Ireland. He has criticised the Catholic Church in many pieces, and favours the legalisation of prostitution. In recent articles he has been critical of Islamic fundamentalism and extremism. In his journalism Myers has opposed the classification of Travellers as an ethnic minority, and has opposed feminist philosophy and the role of trade unions in setting economic policy. He has written against the compensation culture and has opposed state policies towards the Irish language. He has also criticised the prospect of Turkey's accession to the EU.

Other columns have a less political nature, discussing road safety, pet peeves, rugby union, favourite places in Ireland, etc. The fortnightly satirical publication, The Phoenix, regularly lampoons what it sees as his apparent self-obsession, and referring to him by other names such as Kevin Myarse or Colonel MyArse.

Irishness and Nationalism

Myers promotes awareness of Irish soldiers who served in the British Armed Forces, particularly in World War I, arguing that they believed they were doing their patriotic duty as Irishmen. He has criticised the official commemoration of the 1916 Easter Rising, and has raised concerns about uncritically celebrating Irish rebellions of former times. He has been sceptical of the Northern Ireland peace process, and uses the hyphenated term Sinn Féin-IRA in some articles.

The "bastards" controversy

Myers has been an advocate of unrestricted freedom of speech and an opponent of censorship and political correctness. He attracted considerable criticism for "An Irishman's Diary" of 8 February 2005, in which he referred to children of unmarried mothers as "bastards":

Myers issued an unconditional apology two days later, "entirely at [his] own initiative". Irish Times editor Geraldine Kennedy also apologised for having agreed to publish the article. Myers has claimed to have received death threats over his controversial remarks.

Scotland

Myers caused controversy when he referred to Scottish people as obese and dependent on the welfare state:

On the 17 January 2007 he wrote a similar article about Scotland, drawing in the topical issue of the country's possible secession from the United Kingdom or gaining of some other form of independence.

Aid to Africa

In July 2008, Myers wrote an article arguing that providing aid to Africa only results in increasing its population, and its problems. This produced strong reactions, with the Immigrant Council of Ireland making an official complaint to the Garda Síochána alleging incitement to hatred.

Hans Zomer of Dóchas, an association of NGO, and another complainant, took a complaint to the Press Council on the grounds that it breached four principles of the Council's Code of Practice: 1) Accuracy, 3) Fairness and Honesty, 4) Respect for Rights, and 8) Incitement to Hatred. In their case details the Press Council said

In 1974 Myers was approached by the Official IRA who, aware of his contacts, requested a meeting with their loyalist counterparts. A meeting was arranged between Jim Hanna, an Ulster Volunteer Force (UVF) leader and a representative of the Officials. The Europa Hotel, Belfast was chosen because its supposedly tight security would ensure neither side could be armed. Yet both sides managed to smuggle in armed men and Myers described their comical attempts to blend in. Further meetings followed and agreements were reached for the safe return of unfortunates who accidentally found themselves in the other's territory.

Later, at a secret meeting arranged by Myers at the request of the Provisionals. Dáithí Ó Conaill and Brian Keenan had talks with UVF leaders Hanna and Billy Mitchell near Lough Sheelin, County Cavan. Myers summarised the purpose of the talks: The IRA simply wished to discuss the terms of the loyalist surrender and the loyalists wished merely to assure the IRA they had no intention of surrendering. The meeting lasted four hours. Mitchell later recalled that "We just wanted to get to know one another. And we thought we could find a way to call an end to everything." "I really liked David. And neither of us accused the other of anything." That night the two sides had dinner together, followed by a drinking session. Keenan and Mitchell fell asleep, drunkenly in each others arms.

Following the meeting Myers discerned a brief lull in the IRA targeting of UDR soldiers.

He was presenter of the Challenging Times television quiz show on RTÉ during the 1990s. In 2000, he published a collection of his An Irishman's Diary columns (ISBN 1-85182-575-4) and in 2003, he published a novel Banks of Green Willow (ISBN 0-684-02013-0) which was described by John Banville "as fresh as tomorrow's headlines". In 2006, he published Watching the Door (ISBN 1-84351-085-5), about his time as a journalist in Northern Ireland during the 1970s. The book was positively reviewed by The Times, The Guardian, and the New Statesman, while The Independent published a more mixed review that wondered whether there was "an element of hyperbole" in Myers' account.

He is member of the Film Classification Appeals Board (formerly known as the Censorship Board.)

He is a regular contributor to radio programmes on Newstalk 106, particularly Lunchtime with Eamon Keane and The Right Hook. Myers also regularly appears on The Last Word on Today FM.