Friedrichshain is a part of Berlin's borough of Friedrichshain-Kreuzberg, and like Kreuzberg across the river it has its own distinct character, with the result that the new double name is hardly ever used outside government administration. From its creation in 1920 until Berlin's 2001 administrative reform it was a freestanding city borough. Formerly part of East Berlin, it is an inner city locality, adjacent to Mitte, Prenzlauer Berg, Kreuzberg and Lichtenberg. Friedrichshain is named after the Volkspark Friedrichshain, a vast green park located at the north border to Prenzlauer Berg. During the Nazi era, the borough bore the name Horst-Wessel-Stadt.

Friedrichshain counts 3 zones (Ortslagen):

The largely working-class district was created in 1920 when Greater Berlin was established by referendum, incorporating several surrounding settlements. Friedrichshain united the Frankfurter Vorstadt, already part of Berlin, and the villages of Boxhagen and Stralau. It took its name (meaning 'Frederick's Grove') from the Volkspark ('People's Park'), which was planned in 1840 to commemorate the centenary of Frederick the Great’s coronation. Much of the district was settled in the rapid industrialization of the 19th and early 20th centuries, led by growth in manufacturing and crafts. It owed much to the opening of the railway line between Berlin and Frankfurt (Oder) in 1846 (which terminated near the site of today's Berlin Ostbahnhof), and the opening of the first waterworks in 1865 at Stralauer Tor. In 1874 the Krankenhaus im Friedrichshain was opened, Berlin's first hospital beside the university clinic Charité. In the early 1900s, the district's largest employer was the Knorr-Bremse brake factory; the Knorrpromenade, one of Friedrichshain's most attractive streets, was built to house the management.