In 1914, Ireland was on the verge of self-government, but Dublin saw almost a decade of political violence, instead of a peaceful self-rule transition. The outbreak of World War I postponed the Home Rule Bill. It was in 1916 that armed Irish Republicans staged an uprising (Easter Rising) in pursuit of independence and to proclaim an Irish Republic. The rebels took control of strategic points in the city, including the Post Office building on O'Connell Street, and held it for a full week until they were forced to surrender by British forces, leaving some 500 people dead and a large part of the city destroyed. Initially, the Irish population was put off by the rebels, but it gradually began to back them. In 1918, the revolutionary Sinn Fein party won the parliamentary elections and proclaimed a republic, as well as declared its own parliament. 

The Irish War of Independence raged from 1919 to 1921, a conflict between the IRA (then known as the Irish Volunteers) and British troops, where the killing of British policemen and detectives were taken place in Dublin arranged by IRA men under Michael Collins. This agitation peaked with the death of 18 British agents at the hands of the IRA and the British response with the killing of 14 innocent bystanders in Croke Park. In 1921, the IRA destroyed the Custom House, one of Dublin's finest buildings which housed the headquarters of the local government. Five IRA members were killed and over 80 detained.

Britain and Ireland eventually reached a truce and signed the Anglo-Irish Treaty, which provided Ireland's self-rule but actually disestablished the Irish Republic, which angered the IRA and triggered the outbreak of the Irish Civil War in 1922. The militant republicans attacked those who had accepted a compromise with the British. In turn, Winston Churchill ordered British troops to attack the rebels. In the end, the newly appointed Free State government suppressed the rebellion. Ireland remained neutral in World War II, with little damage to Dublin, with exception to the Germans accidentally dropping a bomb in the city's North Wall district. At that time, Dublin was an important destination for Jews fleeing Nazi persecution.