After the election of the Abe Government in 2012, Koizumi was appointed as a Vice-Minister for Reconstruction, focusing on the northeastern region of Japan that was devastated by the March 2011 tsunami and subsequent nuclear disaster. He publicly opposed his father's calls for Japan to abandon nuclear energy immediately. In 2019, Prime Minister Shinzo Abe appointed Koizumi to the Cabinet as Minister of the Environment, a role he retained when Yoshihide Suga succeeded Abe as Prime Minister in September 2020.