One car was burnt in the Amager district and another was torched four hours later in Nørrebro.
“Both cars are completely destroyed, and we are investigating the fires as arson,” Copenhagen Police spokesman Carsten Reenberg told news agency Ritzau.
The incidents marked the fourth consecutive night of car fires in the Copenhagen area and bring the total of vehicles burnt since mid-August to over 50.
A 21-year-old Amager man has been arrested on the suspicion that he was behind at least some of the incidents but around half of the total vehicle fires have happened after the man's arrest.
Police have been cautious about drawing direct parallels to a similar spate of car fires in Sweden.