Karin Wallensteen studied in the University of Michigan in 1993-1994 and in 1996 she graduated from Uppsala University with a degree in Political Science. In 1996-1997, she studied journalism at the University of Gothenburg. She then served as a political advisor to the Minister for Agriculture, Food and Fisheries from 1998 to 2002. In 2003-2004, she took part in the Diplomatic Training Programme in the Ministry for Foreign Affairs. She then joined the Ministry for Foreign Affairs, first being given a diplomatic post in the Embassy of Sweden in Brazil in 2004-2006, and then serving as Deputy Director to the Political Director in the MFA. In 2013, she took a post as Counsellor in the Embassy of Sweden in Addis Ababa. In 2016, she joined the Prime Minister’s Office as Deputy Director-General, in which she is Head of International Affairs. 

In 2019 she was appointed as the State Secretary at the Prime Minister’s Stefan Löfven Office.