Miyazawa held a number of prominent public positions, including Minister of International Trade and Industry (1970–71), Minister of Foreign Affairs (1974–76), Director General of the Economic Planning Agency (1977–78), and Chief Cabinet Secretary (1984–86). He became Minister of Finance under the government of Noboru Takeshita in 1987, but had to resign amid the Recruit scandal.
His government passed a law allowing Japan to send its forces overseas for peacekeeping missions as well as negotiating a trade agreement with the United States. It also introduced financial reforms to address the growing economic malaise in Japan in the 1990s.
Miyazawa later returned to frontbench politics when he was once again appointed finance minister from 1999 to 2002 in the governments of Keizo Obuchi and Yoshiro Mori. His political career ended after he retired from the Diet of Japan in 2003.
Miyazawa was also a member of the Trilateral Commission.