德意志帝国海军（德语：Kaiserliche Marine，直译之意为「皇帝的海军」）是指德意志帝国的海军，存在于1871年至1919年之间。德意志帝国海军最早由普鲁士海军和北德意志邦联海军（Norddeutsche Bundesmarine）为前身所组成的。德国皇帝威廉二世大力扩展海军力量，而形成德意志帝国与大英帝国的军备竞赛，德国海军因而一度发展成世界上仅次于英国皇家海军的强大海军。德意志帝国海军最后大部分在一战西线中损失与在英国斯卡帕湾集结时，在德国海军军官发起的秘密行动中自沉。

德意志帝国海军的船舰通常被命名开头为SMS，为「皇帝陛下的船舰」（德语：Seiner Majestät Schiff）之缩写。

The Imperial German Navy was the Imperial Navy (German:Kaiserliche Marine) – the navy created at the time of the formation of the German Empire. It existed between 1871 and 1919, growing out of the small Prussian Navy (from 1867 the Norddeutsche Bundesmarine), which primarily had the mission of coastal defence. Kaiser Wilhelm II greatly expanded the navy, and enlarged its mission. The key leader was Admiral Alfred von Tirpitz, who greatly expanded the size and quality of the navy, while adopting the sea power theories of American strategist Alfred Thayer Mahan. The result was a naval arms race with Britain as the German navy grew to become one of the greatest maritime forces in the world, second only to the Royal Navy. The German surface navy proved ineffective during World War I; its only major engagement, the Battle of Jutland, was indecisive. However, the submarine fleet was greatly expanded and posed a major threat to the British supply system. The Imperial Navy's main ships were turned over to the Allies, but then were sunk at Scapa Flow in 1919 by German crews.