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. In the mid-16th century Bülkau adopted Lutheranism. During the Catholic Leaguist occupation under Johan 't Serclaes, Count of Tilly (1628–1630), Bülkau suffered from attempts of re-Catholicisation.