The Queen-in-Parliament (or, during the reign of a male monarch, King-in-Parliament), sometimes referred to as the Crown-in-Parliament or, more fully, as the king in Parliament under God, is a technical term of British constitutional law that refers to the Crown in its legislative role, acting with the advice and consent of the lower house and upper house in the case of a bicameral parliament, or the legislature in the case of a unicameral parliament. Bills passed by the houses are sent to the sovereign, or Governor-General, Lieutenant-Governor, or Governor as her representative, for Royal Assent, which, once granted, makes the bill into law; these primary acts of legislation are known as acts of parliament. An act may also provide for secondary legislation, which can be made by the Crown, subject to the simple approval, or the lack of disapproval, of parliament.

Because of the sovereign's place in the enactment of laws, the enacting clause of acts of parliament may mention him or her, as well as the other one or two bodies of parliament. For example, modern Canadian acts of parliament typically contain the following enacting clause: NOW, THEREFORE, Her Majesty, by and with the advice and consent of the Senate and House of Commons of Canada, enacts as follows... Similarly, British Acts of the Parliament will start with: BE IT ENACTED by the Queen's most Excellent Majesty, by and with the advice and consent of the Lords Spiritual and Temporal, and Commons, in this present Parliament assembled, and by the authority of the same, as follows... The phrasing, however, is different when the bill is passed under the provisions of the Parliament Acts 1911 and 1949, without the consent of the Lords. Though the Queen remains a part of the parliaments in realms such as Australia and Tuvalu, the enacting clause for acts of parliament do not mention her, being only The Parliament of Australia enacts and ENACTED by the Parliament of Tuvalu..., respectively.

The Scottish parliament follows a different approach: although its acts require Royal Assent, the concept of Queen-in-Parliament has not been incorporated. Instead of the enacting clause seen in UK acts, acts of the Scottish parliament bear the following text above the long title: The Bill for this Act of the Scottish Parliament was passed by the Parliament on DATE and received Royal Assent on DATE.