Bülkau is a municipality in the district of Cuxhaven, in Lower Saxony, Germany.

Bülkau belonged to the Prince-Archbishopric of Bremen, a territory of imperial immediacy established in 1180.

During the Catholic Leaguist occupation under Johan 't Serclaes, Count of Tilly (1628–1630), Bülkau suffered from attempts of re-Catholicisation.

In 1648 the prince-archbishopric was transformed into the Duchy of Bremen, which was first ruled in personal union by the Swedish Crown – interrupted by a Danish occupation (1712–1715) – and from 1715 on by the House of Hanover.

In 1813 the Duchy of Bremen was restored to the Electorate of Hanover, which – after its upgrade to the Kingdom of Hanover in 1814 – incorporated the duchy in a real union and the ducal territory, including Bülkau, became part of the Stade Region, established in 1823.