In Ireland, the penal laws (Irish: Na Péindlíthe) were a series of legal disabilities imposed in the seventeenth, and early eighteenth, centuries on the kingdom's Roman Catholic majority and, to a lesser degree, on Protestant "Dissenters". Enacted by the Irish Parliament, they secured the Protestant Ascendancy by further concentrating property and public office in the hands of those who, as communicants of the established Church of Ireland, subscribed to the Oath of Supremacy. The Oath acknowledged the British monarch as the "supreme governor" of matters both spiritual and temporal, and abjured "all foreign jurisdictions [and] powers"—by implication both the Pope in Rome and the Stuart "Pretender" in the court of the King of France.

The laws included the Education Act 1695, the Banishment Act 1697, the Registration Act 1704, the Popery Acts 1704 and 1709, and the Disenfranchising Act 1728. Under pressure from the British government, which in its rivalry with France sought Catholic alliances abroad and Catholic loyalty at home, the laws were repealed through a series of relief acts beginning in 1771. The last significant disability, the requirement that Members of Parliament take the Oath of Supremacy, was removed in 1829, after Ireland had been incorporated by the 1800 Acts of Union into a United Kingdom with Great Britain. The Government of Ireland Act 1920 (coming into force during the Irish War of Independence) contained an all-purpose provision in Section 5 removing any remaining sacramental tests technically still in existence.

The penal laws were, according to Edmund Burke, "a machine of wise and elaborate contrivance, as well fitted for the oppression, impoverishment and degradation of a people, and the debasement in them of human nature itself, as ever proceeded from the perverted ingenuity of man." Burke long counselled kinder relations by London with its American and Irish cousins, fearing that the punitive spirit fostered by the British was destroying English character, and would spur violent revolt.

Initially, the dual monarchs of England and Ireland were cautious about applying penal laws to Ireland because they needed the support of the Catholic upper classes to put down the Gaelic Irish rebellion in the Nine Years War (1594–1603). In addition, a significant section of the Catholic aristocracy was composed of Old English, who had traditionally been loyal to English rule in Ireland. However, the ascent of James VI of Scotland to both the English and Irish thrones as James I in 1603 and the eventual victory in the Nine Years War saw a series of coercive new laws put into force. In 1605 the 'Gunpowder Plot' was planned by a group of English Catholics, who were disappointed in their hopes that James would relieve laws against Catholics. This provided a further impetus and justification for restrictive laws on Catholics in Ireland, Scotland and England. In 1607 the Flight of the Earls seeking Catholic help in Europe for a further revolt set the scene for a wholesale Plantation of Ulster by the Lowland Scots and Northern English.

From 1607, Catholics were barred from holding public office or serving in the Irish Army. This meant that the Irish Privy Council and the Lords Justice who, along with the Lord Deputy of Ireland, constituted the government of the country, would in future be Anglicans. In 1613, the constituencies of the Irish House of Commons were altered to give plantation settlers a majority. In addition, Catholics in all three Kingdoms had to pay 'recusant fines' for non-attendance at Anglican services. Catholic churches were transferred to the Anglican Church of Ireland. Catholic services, however, were generally tacitly tolerated as long as they were conducted in private. Catholic priests were also tolerated, but bishops were forced to operate clandestinely. In 1634 the issue of the "Graces" arose; generous taxation for Charles I (whose Queen Henrietta Maria was Catholic) was supported by Irish Catholic landlords on the understanding that the laws would be reformed, but once the tax was passed, Charles' viceroy refused two of the 51 Graces, and subsequent bills were blocked by the Catholic majority in the Irish House of Lords.

Catholic resentment was a factor in starting the Irish Rebellion of 1641 and the establishment of Confederate Ireland from 1642 with Papal support, that was eventually put down in the Cromwellian conquest of Ireland in 1649–53. The Act of Settlement 1652 barred Catholics from membership of Parliament and the major landholders had most of their lands confiscated under the Adventurers' Act 1640. They were also banned from living in towns for a short period.^{[citation needed]} Catholic clergy were expelled from the country and were liable to instant execution when found. Many recusants had to worship in secret at gathering places (such as Mass rocks) in the countryside. In 1666 forty nine Catholics from hiding places in the woods in county Roscommon signed a letter in support of the Pope and protesting the loss of their 'due liberties'. Seventeen Catholic martyrs from this period were beatified in 1992.

Much of this legislation was rescinded after the Restoration in Ireland by Charles II (1660–1685), under the Declaration of Breda in 1660, in terms of worship and property-owning, but also the first Test Act became law from 1673. Louis XIV of France increased Protestant paranoia in Europe when he expelled the Huguenots from France in 1685, and took his policy from the hard-line Bishop Bossuet. Following the flight from England to Ireland by James II caused by the English Glorious Revolution in 1688, the decisions of the Catholic-majority Patriot Parliament of 1688–9 in Dublin included a complete repeal of the 1660s land settlements. These were reversed after the largely Roman Catholic Jacobites that sided with King James then lost the Williamite war in Ireland in 1689–91. His opponents William III and Mary II were grandchildren of King Charles I, and so the war ultimately decided whether Catholic or Protestant Stuarts would reign.

The war ended with the Treaty of Limerick agreed by Sarsfield and Ginkel in October 1691. This provided in article 1 that: