The 32-year-old victim had been beaten and stabbed to death and robbed of 5,000 kronor ($760).
Police found his body in a wooded area in the Frösunda district of Solna, north of Stockholm.
The girls, aged 16 and 18, then met up with the man at a petrol station and asked him to withdraw cash from a teller machine.
In its ruling, the court stated that the girls had supported themselves by tricking unwitting male victims contacted on dating websites.
I've been hearing my girlfriends discuss their wins and losses with a variety of online-dating phone apps, so I'm breaking down the newest means of tech-based courtship.