Wilhelmstraße, or Wilhelmstrasse (see ß; German pronunciation: [ˈvɪlhɛlmˌʃtʁaːsə]; transl. William Street) is a major thoroughfare in the central Mitte and Kreuzberg districts of Berlin, Germany. Until 1945, it was recognised as the centre of the government, first of the Kingdom of Prussia, and later of the unified German Reich, housing in particular the Reich Chancellery and the Foreign Office. The street's name was thus also frequently used as a metonym for overall German governmental administration: much as the term "Whitehall" is often used to signify the British governmental administration as a whole. In English, "the Wilhelmstrasse" usually referred to the German Foreign Office.

The Wilhelmstraße runs south from the Spree riverside through the historic Dorotheenstadt quarter to the Unter den Linden boulevard near Pariser Platz and Brandenburg Gate, where it takes on a line slightly east of south through adjacent Friedrichstadt, until its juncture with Stresemannstraße near Hallesches Tor in Kreuzberg, an overall distance of about 2.4 km (1.5 mi).

Further south of Unter den Linden it passes the nowadays built-over former Wilhelmplatz vis-à-vis Voss-Straße, it crosses Leipziger Straße near Leipziger and Potsdamer Platz, and Niederkirchnerstraße, known until after World War II as Prinz-Albrecht-Straße. At its southern end, Wilhelmstraße originally met with Friedrichstraße, which runs roughly parallel to the east, on the Belle-Alliance circus, before the street course was westerly redirected to the Stresemannstraße junction about 1970.

Between Unter den Linden and parallel Behrenstraße, the road is closed for motor vehicles as a protection of the Embassy of the United Kingdom.

Frederick William I, from 1713 King in Prussia and Elector of Brandenburg, had the southwestern Friedrichstadt quarter of his Berlin residence significantly enlarged, whereby the premises up to the Berlin Customs Wall (on present-day Stresemannstrasse) were developed as an affluent residential area. In 1731 the Husarenstraße (Street of the Hussars) was built as a north-south thoroughfare of the Baroque city layout, where many Huguenots, who had fled from France, as well as expelled members of the Moravian Church settled. Several personal confidants of the king had large city palaces erected, most notably General Kurt Christoph Graf von Schwerin and the French Baron François Mathieu Vernezobre de Laurieux, who took his residence in the later Prinz-Albrecht-Palais. The street was renamed Wilhelmstraße in honour of the king, who had died in 1740.

Originally a wealthy residential street, with a number of palaces belonging to members of the Hohenzollern royal family, the Wilhelmstrasse developed as a Prussian government precinct from the mid 19th century. In 1858 King Frederick William IV acquired the former Palais Schwerin on No. 73. This building now called Palace of the Reich President housed an administrative seat of the Prussian minister for the Royal Household, from 1861 led by Alexander von Schleinitz. In 1869 the nearby Palais Schulenburg residence of late Prince Antoni Radziwiłł, built in 1738/39 on No. 77, was purchased by the Prussian state government at the behest of Schleinitz' opponent Minister-President Otto von Bismarck. Rebuilt from 1875 until 1878, it served as his official seat as German chancellor. Congress of Berlin in 1878 and Berlin Conference in 1884/1885 took there place. The next door building on No. 76 was used for the chancellery's Foreign Office department.

Several further governmental departments took their seat on Wilhelmstrasse, such as the Reich Ministry of Finance (No. 61), the Imperial Colonial Office (No. 62), the Prussian state ministry (No. 63), the Reich Ministry of Food and Agriculture (No. 72), and the Reich Ministry of Transport (No. 79, from 1919). The lavish Palais Strousberg of bankrupt "railway king" Bethel Henry Strousberg on No. 70 was bought by Prince Hugo of Hohenlohe in an 1876 auction and rented out to the British ambassador Lord Ampthill, until it was finally purchased by the United Kingdom in 1884. In 1877 the Borsig Palace was erected on the corner with Voss-Strasse.

After World War I the Palais Schwerin was sold by exiled Emperor Wilhelm II to the Weimar Republic government and in 1919 became the residence of the first Reich President of Germany, Friedrich Ebert. Until the death of his successor Paul von Hindenburg in 1934, the President's official residence was at Wilhelmstraße 73, where he could watch the torchlight parade on the night of the Nazi Machtergreifung on 30 January 1933, after he had sworn in Adolf Hitler as German chancellor. Hitler addressed the cheering crowds on Wilhelmstrasse from a window of a modern chancellery annex building erected in 1930. Styling himself "Führer and Reich Chancellor" from 1934, he regarded the residence inadequate and ordered the construction of the vast New Reich Chancellery according to plans designed by Albert Speer. This building, a prime example of Nazi architecture, stood immediately south of the old Chancellery, on the corner of the Wilhelmstrasse and the Voss Strasse, and its official address was Voßstraße 4.