Kostyantyn Ivanovych Gryshchenko (also spelled Hryshchenko; Ukrainian: Костянтин Іванович Грищенко; born 28 October 1953) is a Ukrainian diplomat and politician.

Since Ukraine gained independence, Kostyantyn Gryshchenko has served in a succession of senior positions with responsibilities ranging from arms control and regional security to education and public health. He served as Vice Prime Minister of Ukraine (2012–2014), Minister of Foreign Affairs of Ukraine (2003–2005 and 2010–2012) and First Deputy Secretary of the National Security and Defense Council of Ukraine (2008–2010). Ambassadorial appointments include: Head of Mission of Ukraine to NATO and the Ambassador of Ukraine to Belgium, the Netherlands and Luxembourg (1998–2000), Ambassador to the United States (2000–2003) and Ambassador to the Russian Federation (2008–2010). In addition to his posts in the Ukrainian Government, Kostyantyn Gryshchenko participated in personal capacity in a number of high-profile bodies focused chiefly on various aspects of regional and international security: 1991 –Deputy Chief Inspector for biological weapons of the United Nations Special Commission in Iraq (UNSCOM); 1995–1998 –Member of Council of Founders, Geneva Center for Security Policy; 1999–2003 Member of the Advisory Board on Disarmament Matters to the UN Secretary General (in 2003 –Chairman of the Board); 2000–2003 –Member, United Nations Monitoring, Verification and Inspection Commission (UNMOVIC) and 2003–2006, Member of the Board of Directors of Transatlantic Partners Against AIDS. Kostyantyn Gryshchenko holds the diplomatic rank of Ambassador Extraordinary and Plenipotentiary.

In 1975 Kostyantyn Gryshchenko graduated with honors from Moscow State Institute of International Relations with a specialty in international law. Besides his native Ukrainian and Russian languages he is fluent in English and French.

1976–1980 –served as staff member of the United Nations Secretariat in New York City.

From 1981–1991 held various diplomatic positions in the Ministry of Foreign Affairs of the USSR.

Following the collapse of the Soviet Union Kostyantyn Gryshchenko returned to Kyiv where he took up work in the Ministry of Foreign Affairs of newly independent Ukraine.

1995–1998 – Deputy Minister of Foreign Affairs of Ukraine with responsibilities covering arms control and disarmament, European security, the Commonwealth of Independent States, Russian Federation, Middle East, Asia, Africa and the Pacific region. He played a key role in negotiating a number of crucial international agreements aimed at strengthening the independence, territorial integrity and security of Ukraine. During this time Kostyantyn Gryshchenko initiated a large scale program for professional diplomatic training for newly recruited MFA personnel in a number of the EU countries and in the United States. Many of the graduates later became leading diplomats in the Ukrainian diplomatic service.

1998–2000 – Head of Ukrainian Mission to NATO, Ambassador of Ukraine to Belgium, the Netherlands and Luxembourg, Permanent Representative to the Organization for the Prohibition of Chemical Weapons (OPCW) in The Hague.