The 36-year-old leader agreed to take the test on Friday following pressure from political opponents who slammed the behaviour.
At a news conference, reporters questioned whether the prime minister would have been able to make a snap governmental decision if required.
Marin denies doing anything illegal, and says her ability to function as PM was ‘really good’.
She has defended her actions, and says she has never used drugs, even as a teenager.
A government statement confirmed Marin was tested for cocaine, amphetamines, cannabis and opioids, and the PM paid for the test herself.
It comes as women right around the world post videos in solidarity with Finland’s leader