Flensburger Brauerei is a brewery located in Flensburg, Schleswig-Holstein, Germany. It was founded on September 6, 1888, by five citizens of Flensburg. It is one of the last breweries in the country that is not owned by a large brewing group.

The brewery used to cut pieces of ice from frozen lakes in winter before modern cooling methods were invented, in order to keep its underground storage facilities cool in summer. The brewery operates its own water well, fed by an underground vein of very old melted water from the Ice Age, originating from Scandinavia.