The four were charged with criminal conspiracy relating to a terrorist enterprise on Friday after being rounded up at their homes in the Paris region on Tuesday, sources say.
One, a 22-year-old from Vitry-sur-Seine, is presumed to be the leader and in contact with "facilitators" in the conflict zoone.
At least two of the three others are believed to have gone to fight in Syria themselves.
Three of the four were born in France, the other in Morocco.
A woman who was detained with them has been released without charge.
Investigators hope to establish how many jihadis have one from France to Syria thanks to the network.
Intelligence agencies have identified 440 people have been or wish to go to Syria to fight Bashar al-Assad's regime with jihadi groups, a figure that has risen sharply this year.
About half that number are in the country at the moment, they estimate, about 12 have been killed, one or two are prisoners of the regime, and 50-60 have returned.
About 20 legal inquiries are taking place and three have been charged on returning from Syria.
Interior Minister Manuel Valls has judged the development "very worrying" and anti-terror police believe that returned fighters represent the highest risk of launching attacks on French soil.