His or Her Majesty's Privy Council in Ireland, commonly called the Privy Council of Ireland, Irish Privy Council, or in earlier centuries the Irish Council, was the institution within the Dublin Castle administration which exercised formal executive power in conjunction with the chief governor of Ireland, who was viceroy of the British monarch. The council evolved in the Lordship of Ireland on the model of the Privy Council of England; as the English council advised the king in person, so the Irish council advised the viceroy, who in medieval times was a powerful Lord Deputy. In the early modern period the council gained more influence at the expense of the viceroy, but in the 18th century lost influence to the Parliament of Ireland. In the post-1800 United Kingdom of Great Britain and Ireland, the Irish Privy Council and viceroy Lord Lieutenant had formal and ceremonial power, while policy formulation rested with a Chief Secretary directly answerable to the British cabinet. The council comprised senior public servants, judges, and parliamentarians, and eminent men appointed for knowledge of public affairs or as a civic honour.

Dublin Castle was the centre of the government of Ireland under English and later British rule. "Dublin Castle" is used metonymically to describe British rule in Ireland. The Castle held only the executive branch of government and the Privy Council of Ireland, both appointed by the British government. The Castle did not hold the judicial branch, which was centred on the Four Courts, or the legislature, which met at College Green until the Act of Union 1800, and thereafter at Westminster.