The centre-right government has been keen to get Nordea to shift its headquarters to Helsinki, campaigning on Finland's membership in the euro zone and the EU's banking union, and predictable policy outlook.
"Welcome to Finland Nordea HQ. Finland's membership in the Banking Union provides a stable business environment," Finland's Finance Minister Petteri Orpo wrote on Twitter.
Losing Nordea will be a blow to Swedish prestige as it seeks to attract financial firms when Britain leaves the European Union.
The Swedish finance minister said the move could reduce risks to the economy from the outsized banking sector.
"Having a banking headquarters also comes with increased risks for tax payers," she said. "That is exactly why we in the Swedish parliament have found it important to have tough rules to safeguard financial stability."
Opposition politicians were fast to voice their dissatisfaction with Nordea's decision, although they didn't agree on who was to be blamed.
"Yet again Social Democratic policies lead to companies fleeing Sweden. We should be a country to which people and companies move, not the other way around," Centre Party leader Annie Loof told TT news agency.
Jonas Sjostedt, leader of the Left Party, accused Nordea of being greedy.
"To me, it is a matter of banks doing their part. The banks receive indirect support from society and have state guarantees, and they should pay back too," he told TT.