From 1984 to 1990 Christian Schmidt was a town councillor in his hometown of Obernzenn and member of the District Council for Neustadt an der Aisch-Bad Windsheim.

[3] Schmidt was named Parliamentary State Secretary in the Federal Ministry of Defence by Chancellor Angela Merkel on 23 November 2005.

In this capacity he served as parliamentary and political representative for three Ministers of the Defence; Franz Josef Jung, Karl-Theodor zu Guttenberg and Thomas de Maizière.

His time in office has seen several landmark events including the investigation into the wartime activities of World War II German flying ace Werner Mölders (2007), the reorientation of the Federal Republic's armed forces (since 2010) and the resignation of Defence Minister zu Guttenberg in the wake of a plagiarism scandal (2011).

Following the resignation of zu Guttenberg in 2011 Schmidt remained in office and was re-confirmed to the post by the new Minister for Defense, Thomas de Maiziere.

In the negotiations to form a coalition government following the 2013 federal elections, he was part of the CDU/CSU delegation in the working group on foreign affairs, defense policy and development cooperation, led by de Maizière and Frank-Walter Steinmeier.

In response to a 2016 collapse in milk prices, Schmidt rolled out an emergency package of at least €100 million for the country's dairy farmers, including loans and tax relief.

[4] Also during his time in office, Germany culled 776,000 farm chickens, turkeys, ducks and other types of poultry between November 2016 and January 2017 to combat bird flu.

[5] In November 2017, Schmidt angered most politicians by breaking an agreement not to back a European Union proposal to extend the use of glyphosate for another five years, a measure opposed by Environment Minister Barbara Hendricks of the SPD, who had secured a guarantee of a non-positive vote just minutes before;[6] it is usual practice that Germany abstains in EU votes if ministers from different governing parties disagree on a policy.

Following the incident, Chancellor Merkel publicly scolded Schmidt, arguing that he should not have voted in favor against the wish of his colleague and in breach of government instructions.

In 2019, Schmidt was appointed by the Federal Ministry of the Interior, Building and Community to serve on the committee that oversaw the preparations for the 30th anniversary of German reunification.

[18] The draft was also criticised by Bisera Turković, the Foreign Minister of Bosnia and Herzegovina and the Iranian embassy, claiming it "consolidates the ethnic divisions".

[20] Russia and China had opposed Schmidt's appointment, do not recognize the legality and legitimacy of Schmidt’s election and refuse to recognise his authority, as he was appointed without a corresponding United Nations Security Council resolution nor was he chosen or approved on a broad consensus by the Peace Implementation Council, as was the case for previous High Representatives.

[26][27] At the same time, Fadil Novalić, whom Nikšić succeeded as Prime Minister thanks to Schmidt's intervention, refused to concede the power and continues contesting his forceable deposing as illegal and unconstitutional.

[28] In June 2023, the National Assembly of Republika Srpska voted to suspend rulings by the Constitutional Court of Bosnia and Herzegovina and stopping publishing the High Representative's decrees and laws in the official gazette.