The Christian Democratic Union of Germany (German: Christlich Demokratische Union Deutschlands [ˈkʁɪstlɪç demoˈkʁaːtɪʃə ʔuˈni̯oːn ˈdɔʏtʃlants], CDU [ˌtseːdeːˈʔuː] ^ⓘ) is a Christian democratic and conservative political party in Germany. It is the major party of the centre-right in German politics. Friedrich Merz has been federal chairman of the CDU since 31 January 2022, and has served as the Chancellor of Germany since 6 May 2025.

The CDU is the largest party in the Bundestag, the German federal legislature, with 208 out of 630 seats, having won 28.5% of votes in the 2025 federal election. It forms the CDU/CSU Bundestag faction, also known as the Union, with its Bavarian counterpart, the Christian Social Union in Bavaria (CSU). The group's parliamentary leader has been Jens Spahn since 5 May 2025.

Founded in 1945 as an interdenominational Christian party, the CDU effectively succeeded the pre-Nazi era Catholic Centre Party, with many former members joining the party, including its first leader Konrad Adenauer. The party also included politicians of other backgrounds, including liberals and conservatives. As a result, the party claims to represent "Christian-social, liberal and conservative" elements. The CDU is generally pro-European in outlook. Black is the party's customary and historical electoral colour. Other colours include red for the logo, orange for the flag, and black-red-gold for the corporate design.

The CDU leads the federal government in a grand coalition with the Social Democratic Party of Germany (SPD), after returning as the largest party in the 2025 federal election. It previously led the federal government from 1949 to 1969, 1982 to 1998, and 2005 to 2021. Germany's three longest-serving post-war Chancellors have all come from the CDU, specifically: Helmut Kohl (1982–1998), Angela Merkel (2005–2021), and Konrad Adenauer (1949–1963). The party also currently leads the governments of seven of Germany's sixteen states.

The CDU is a member of the Centrist Democrat International, the International Democracy Union, and the European People's Party (EPP). It is the largest party in the EPP with 23 MEPs. Ursula von der Leyen, the current President of the European Commission, is also a member of the CDU.

Immediately following the end of World War II and the foreign occupation of Germany, simultaneous yet unrelated meetings began occurring throughout the country, each with the intention of planning a Christian-democratic party. Consequently, the CDU was established in Berlin on 26 June 1945 and in Rheinland and Westfalen in September of the same year.

The founding members of the CDU consisted primarily of former members of the Centre Party, the German Democratic Party, the German National People's Party, and the German People's Party. In the Cold War, years after World War II up to the 1960s (see Vergangenheitsbewältigung), the CDU attracted conservative, anti-communist, former Nazis as well as Nazi collaborators into its higher ranks (like Hans Globke and Theodor Oberländer but also future CDU chairman and West German chancellor Kurt Georg Kiesinger). A prominent member was theologian Eugen Gerstenmaier, who became Acting Chairman of the Foreign Board (1949–1969).

The result of these meetings was the establishment of an inter-confessional (Catholic and Protestant alike) party influenced heavily by the political tradition of liberal conservatism. The CDU experienced considerable success gaining widespread support from the time of its creation in Berlin on 26 June 1945 until its first convention on 21 October 1950, at which future West German Chancellor Konrad Adenauer was named the first Chairman of the party.