Kostiantyn Matsiyevych (Ukrainian: Костянтин Андріанович Мацієвич) (May 18, 1873 in Deremezna, Vasilkovsky Uyezd, Kiev Governorate[1] – April 2, 1942 in Prague[2]) was a Ukrainian statesman and public figure, scientist, agrarian and diplomat.

[3] He worked then in societies farmhouses of Poltava and Kharkiv provinces, was an agronomist of Saratov regional council.

In Kharkiv he edited the magazines Farmers, Agronomy Journal and a newspaper of Agriculture (1907-1915).

He was a member of the Ukrainian delegation at the peace conference between Soviet Ukraine and Russia (May–October 1918) and the Committee to negotiate trade agreements.

From February 13 to April 9, 1919 he was the Minister of Foreign Affairs of the Ukrainian People's Republic,[5] in the office of Serhiy Ostapenko.