The lawyer for the Danish-Turkish man -- who during his trial denied fighting for IS but admitted working as a baker for the group in Syria -- told broadcaster TV2 his client would appeal Fridays ruling.
The court order comes at a time of growing concerns about increased radicalisation among Muslims in Europe in the wake of attacks in countries such as France, Germany and Britain.
Danish media identified the man Enes Ciftci, who was born and raised in Denmark, Reuters reported.
Ciftci was originally sentenced to seven years in prison for allowing himself to be recruited in 2013 by IS to commit attacks in Syria, but allowed to keep his passport.
Prosecutors appealed that sentence, leading to Fridays hearing.
Last year, Denmarks Supreme Court stripped a Danish-Moroccan bookseller of his citizenship after he was jailed for inciting terrorism.