Marin was born in Finland's capital city Helsinki in 1985, and lived in various cities around the country before her family settled in the southern city of Tampere.
In Tampere, Marin lived and was brought up in a same-sex family with her mother and her mother's partner.
Marin describes herself as coming from a "rainbow family," and in 2015 she told Finnish media how growing up she felt "invisible" because her family "weren't recognized as a real family."
Her upbringing had a profound affect on her politics. "For me, people have always been equal. It's not a matter of opinion. That's the foundation for everything," she said in a 2015 interview.
next slide will load in 15 secondsSkip AdSkip AdThe first person in her family to go to university, Marin graduated from Prikkala High School in 2004 and went on to study Administrative Sciences at the University of Tampere.
In 2012, at just 27 years old, Marin became head of the city council in Tampere, which has a population of around 230,000 people.
While still the head of the Tampere city council, Marin was elected as an MP for the Social Democrat Party in 2015, representing the region of Pirkanmaa.
Since June, she has held the position of Transport and Communications Minister. In the picture below she can be seen on the far-right in the second row.
The former prime minister of Finland Antti Rinne resigned last Tuesday after intense criticisms over the way he handled a postal strike.
She will take power amid a strike by several of the country's largest companies, Reuters said. The strike is estimated to result in a loss of about 500 million euros ($550 million), according to the Confederation of Finnish Industries.
Source: Reuters
next slide will load in 15 secondsSkip AdSkip AdThe incident paved the way for Marin to take the top job after the Social Democratic party voted her in to take Rinne's place on Sunday.
She is due to be sworn in on Tuesday, making her the youngest serving prime minister in the world currently.
"We have a lot of work ahead to rebuild trust," Marin told reporters after she won the premiership.
"I have never thought about my age or gender, I think of the reasons I got into politics and those things for which we have won the trust of the electorate," she continued.
Source: Business Insider
Her achievement is no mean feat when you compare her age to other world leaders —Donald Trump was 70 when he became US president and Britain has not had a prime minister under 40 since 1806.
Marin joins other young world leaders, including 39-year-old Jacinda Ardern, New Zealand's prime minister, and 35-year-old Oleksiy Honcharuk, the prime minister of Ukraine.
Marin's age and progressive politics, along with the fact that she is a new mom, have garnered comparisons to Arden.
Source: BBC