Ollongren started her career in the civil service at the Ministry of Economic Affairs, becoming a policymaker in the area of Central and Eastern Europe there in 1992, in which capacity she trained young political parties of the newly established democracies in the area. She was head of parliamentary affairs within the ministry until 2001, and director of European Integration and Strategy from 2001 to 2004, and became Deputy Director General of the ministry in 2004. In 2007, she moved to the Ministry of General Affairs, the department headed by the Prime Minister, becoming Deputy Secretary General. She became Secretary General of the ministry in 2011.
After the 2014 local election, in which the Democrats 66 became the largest party of Amsterdam and entered the city’s government, Ollongren became an alderwoman and second deputy mayor in Amsterdam, taking office on 18 June 2014. Her portfolio as alderwoman was extensive, including economic affairs, seaport, airport, participation, art, culture, local media, monuments and the city centre. On 18 September 2017, the city’s mayor Eberhard van der Laan announced in an open letter to the people of Amsterdam that he would step back from his public responsibilities due to ill health, leaving Kajsa Ollongren to exercise these responsibilities in his stead from 19 September onward. The day after his death, on 6 October, Ollongren became acting Mayor of Amsterdam
Minister of the Interior
On 26 October 2017, Ollongren was appointed as Minister of the Interior and Kingdom Relations in Mark Rutte’s third cabinet, succeeding Ronald Plasterk. She also became the second of the cabinet’s three Deputy Prime Ministers, serving alongside Hugo de Jonge and Carola Schouten.