Sanna Marin, Finland's 34-year-old Minister of Transport, will also become the country's youngest prime minister ever when she is sworn in on Tuesday.
On Sunday, Marin narrowly won a vote among Social Democratic lawmakers, according to Reuters, replacing defiant Prime Minister Antti Rinne, who resigned on Tuesday after the Center Party coalition partner said it had lost confidence in him over his handling of a postal workers' strike.
The Prime Minister-elect told reporters she has "a lot of work ahead to rebuild confidence," according to Reuters.
"I never thought about my age or gender, I think about the reasons why I got into politics and the things that we have gained the trust of voters," the news agency Agence France-Presse reported that she said.
Marin rose through the ranks after leading the city council in her industrial hometown of Tampere when she was 27, according to Reuters.
Social Democrats are the largest party in a five-government coalition, according to Reuters. Marin took the top spot after defeating the leader of the party's parliamentary group, Antti Lindtman.
The five major parties in Finland's parliament are now all headed by women, four of whom are in their 30s: Li Andersson, 32, leader of the Left Alliance; Maria Ohisalo, age 34, heads the Green League; The center party is led by Katri Kulmuni, 32; and Anna-Maja Henriksson, 55, is the leader of the Swedish People's Party in Finland.