The Anglo-German Naval Agreement (AGNA) of 18 June 1935 was a naval agreement between the United Kingdom and Germany regulating the size of the Kriegsmarine in relation to the Royal Navy.

The Anglo-German Naval Agreement fixed a ratio whereby the total tonnage of the Kriegsmarine was to be 35% of the total tonnage of the Royal Navy on a permanent basis. It was registered in League of Nations Treaty Series on 12 July 1935. The agreement was abrogated by Adolf Hitler on 28 April 1939.

The Anglo-German Naval Agreement was an ambitious attempt on the part of both the British and the Germans to reach better relations, but it ultimately foundered because of conflicting expectations between the two countries. For Germany, the Anglo-German Naval Agreement was intended to mark the beginning of an Anglo-German alliance against France and the Soviet Union, whereas for Britain, the Anglo-German Naval Agreement was to be the beginning of a series of arms limitation agreements that were made to limit German expansionism. The Anglo-German Naval Agreement had been controversial ever since because the 35:100 tonnage ratio allowed Germany the right to build a navy beyond the limits set by the Treaty of Versailles and because London had made the agreement without consulting the French or Italian governments.

Part V of the 1919 Treaty of Versailles had imposed severe restrictions on the size and capacities of Germany's armed forces. Germany was allowed no submarines, no naval aviation, and only six obsolete pre-dreadnought battleships; the total naval forces allowed to the Germans were six armoured vessels of no more than 10,000 tons displacement, six light cruisers of no more than 6,000 tons displacement, twelve destroyers of no more than 800 tonnes displacement, and twelve torpedo boats.

Through the interwar years German opinion had protested these restrictions as harsh and unjust, and demanded that either all the other states of Europe disarm to German levels, or Germany be allowed to rearm to the level of all the other European states. In Britain, where after 1919 guilt was felt over what was seen as the excessively harsh terms of Versailles, the German claim to "equality" in armaments often met with considerable sympathy. More importantly, every German government of the Weimar Republic was implacably opposed to the terms of Versailles, and given that Germany was potentially Europe's strongest power, from the British perspective it made sense to revise Versailles in Germany's favour as the best way of preserving the peace; moreover, by allowing Germany some rearmament, Britain might win it to a position favorable to British interests, and, by offering a position better than Versailles but short of free rearmament, temper German militarism. The British attitude was well summarised in a Foreign Office memo from 1935 that stated "... from the earliest years following the war it was our policy to eliminate those parts of the Peace Settlement which, as practical people, we knew to be unstable and indefensible".

The change of regime in Germany in 1933 caused alarm in London, but there was considerable uncertainty regarding Hitler's long-term intentions. The Secretary to the Committee of Imperial Defence (CID), Sir Maurice Hankey, visited Germany in August 1933, and wrote a report of his impressions of the "New Germany" that October. His report concluded with the words:

That uncertainty over Hitler's ultimate intentions in foreign policy was to colour much of the British policy towards Germany until the outbreak of World War II definitively resolved the question in favor of the former in 1939.

Equally important as one of the origins of the agreement were the deep cuts made to the Royal Navy after the Washington Naval Conference of 1921–1922 and the London Naval Conference of 1930. The cuts imposed by the two conferences, combined with the effects of the Great Depression, caused the collapse of much of the British shipbuilding industry in the early 1930s. That seriously hindered efforts at British naval rearmament later in the decade, leading the British Admiralty to value treaties with quantitative and qualitative limitations on potential enemies as the best way of ensuring the Royal Navy's sea supremacy. Maiolo argues that it was actually of little importance whether potential enemies placed voluntary limitations on the size and the scale of their navies. In particular, Admiral Sir Ernle Chatfield, the First Sea Lord between 1933 and 1938, came to argue in favour of such treaties. They promised a standardised classification of different warships and discouraged technical innovations, which under existing conditions the Royal Navy could not always hope to match. Chatfield especially wished for the Germans to do away with their Deutschland-class Panzerschiffe (known in the London press as "pocket battleships"), as such ships, embracing the characteristics of both battleships and cruisers, were dangerous to his vision of a world of regulated warship types and designs. As part of the effort to do away with the Panzerschiffe, the British Admiralty stated in March 1932 and again in the spring of 1933 that Germany was entitled to "a moral right to some relaxation of the treaty [of Versailles]".