Altenwerder (German pronunciationⓘ) is a quarter in the Harburg borough of the Free and Hanseatic city of Hamburg in northern Germany.

In the 1970s the city of Hamburg announced the formal dispossession of all property to build the Container Terminal Altenwerder.

In addition, feudal registers of the Corvey monastery give indirect evidence that Altenwerder may have been used or settled before 844.

Since parts of the land had become uninhabitable due to a series of storm surges, among them especially the Cäcilien flood in 1412, Altenwerder was newly diked on the basis of a treaty of February 27, 1418 by the two sovereigns Johann Slamsdorp, the Prince-Archbishop of Bremen and the Duke of Brunswick-Lüneburg.

In 2006 according to the statistical office of Hamburg and Schleswig-Holstein, the quarter Altenwerder has a total area of 6.8 km2.