A member of the Social Democratic Party of Germany (SPD), he has served as Federal Minister of Defence in the cabinet of Chancellor Olaf Scholz since 19 January 2023.

[17] In the negotiations to form a fourth coalition government under Chancellor Angela Merkel's leadership following the 2017 federal elections, Pistorius was part of the working group on internal and legal affairs, led by Thomas de Maizière, Stephan Mayer and Heiko Maas.

In the 2019 SPD leadership election, Pistorius was a candidate for the position as the party's co-chair, together with Saxony State Minister Petra Köpping.

[21] This came as a surprise to many political observers, with SPD co-leader Lars Klingbeil and Bundestag Armed Forces Commissioner Eva Högl being floated most often as replacements.

[28] In March 2023, Pistorius participated in the first joint cabinet meeting of the governments of Germany and Japan in Tokyo, chaired by Chancellor Scholz and Prime Minister Fumio Kishida.

[29] In October 2023, he joined the first joint cabinet retreat of the German and French governments in Hamburg, chaired by Scholz and President Emmanuel Macron.

[30][31] In July 2024, Christian Lindner warned Boris Pistorius that no additional funds would be provided for military modernization beyond what the coalition government had already agreed upon.

This followed a budget decision that left Pistorius, responsible for revitalizing Germany's defenses amid increased security concerns following Russia's invasion of Ukraine, feeling disappointed.

This budgetary restraint came as the IMF noted that Germany's low public infrastructure investment was affecting its economic growth, despite having the lowest debt-to-GDP ratio in the G7.

[47] In 2021, he demanded that Germany order the messaging program Telegram removed from Apple Inc.'s and Google's app stores if it continues to ignore requests to help track down extremist content.