Saarenheimo graduated from the University of Helsinki in 1989 and continued studying afterwards, receiving his doctorate in economics in 1994. He has also worked as a researcher at the university.[3] Saarenheimo filled several positions at the Bank of Finland. His last post was as Chief Adviser and Head of the Monetary and Research Policy Department.[4] Besides, he has served as the Executive Director for Nordic and Baltic countries at the International Monetary Fund and as National Expert at the European Commission.[3]
Saarenheimo became the Permanent Under-Secretary for International and Financial Market Affairs at the Ministry of Finance in September 2013.[3][5] Because of this position, he was granted membership of the Eurogroup Working Group, an advisory body that prepares the monthly meetings of the Eurogroup. He also became a member of the board of directors of the European Financial Stability Facility, the eurozone's emergency fund to address government debt.[3]
On 1 April 2020 he became President of the Eurogroup Working Group (EWG) after his predecessor Hans Vijlbrief had resigned in order to fill a cabinet position in the Netherlands.[6] Saarenheimo had been elected by the EWG in February, and that decision was later ratified by the Eurogroup. He simultaneously became President of the Economic and Financial Committee.[7] Saarenheimo had been a candidate for EWG president before in 2018, but withdrew.[8]