Kaarlo Castrén (28 February 1860 – 19 November 1938) was a Finnish politician and Prime Minister of Finland.^[1] He represented the National Progressive Party.

Castrén was born in Turtola and graduated in 1887 as a Bachelor of Law. From 1888 to 1892, he worked in the finance division of the Senate of Finland, and from 1888 to 1898 in the Castrén & Snellman attorneys-at-law office.

From 1892 to 1904, Castrén was a member of the board in the Kansallis-Osake-Pankki bank. He attended the state board meetings in 1894 and from 1905 to 1906. He was Senator from 1908 to 1909, after which he founded an attorney-at-law office. In 1916, Castrén was elected as the director of Kansallis-Osake-Pankki.

In November 1918, Castrén was named Minister of Finance.^[2] He served as Prime Minister of Finland from 17 April to 15 August 1919. His government gave a proposal of the republic form of government in Finland, and after the proposal was accepted, the government disbanded.

Castrén died in Helsinki.

• Kaarlo Castrén Cabinet