Eeli Tolvanen (Nashville Predators) began the scoring 2:26 into the game for Finland, which outshot Germany 11-2 in the first period and 38-15 overall.
The Germans tallied twice on six shots in the second frame, while goaltender Mathias Niederberger made 14 of his 36 saves in the period
"Their goalie was making big saves and moving really well," said Colorado Avalanche and Finnish forward Mikko Rantanen to the IIHF's official website. "He was their best player."
Rantanen finished the game with three shots on goal and a minus-2 rating in 19:41 of ice time while on the Finns' top line.
Finland is in second place in Group B with a 4-0-1-1 record and 13 points. The country plays the United States (4-2-0-0) on Tuesday to close out the preliminary round.
The Finns need a regulation win against USA, which leads the group with 16 points, to secure the top spot from the pool into the quarterfinals.