"These people turned their backs on Denmark and used violence to fight against our democracy and freedoms. They constitute a threat to our security. They are undesirable in Denmark," Prime Minister Mette Frederiksen said in a statement.
The Social Democratic government's initiative, which is backed by a majority of parties in parliament, would involve stripping the citizenship of dual nationals while they are abroad, with only an expedited administrative decision.
Until now, a court ruling was needed.
"There is a risk that the Kurdish-controlled Isis camps in the border region collapse, and that foreign fighters with Danish citizenship make their way to Denmark," Frederiksen said.
The expedited bill will be considered by parliament in the coming weeks and could be adopted within a month.
In early September, Denmark's justice minister said there were 36 jihadists who had travelled from Denmark to fight in the region.
Among them, 10 had their residency permits withdrawn and 12 had been jailed.
In March, under the previous government, Denmark adopted a law depriving children born abroad to Danish jihadists the right to citizenship.
