The six were sentenced to eight years' hard labour, a type of punishment which does not exist in French justice.
Chad allowed the aid workers to return to France to serve their sentences.
They were convicted on 26 December of trying to fly out 103 children who they said were Sudanese orphans. But most were Chadians, and not orphans.
The four men and two women were also sentenced to pay a $9m (£4.5m) fine.
They were flown to France two days later under the terms of a 1976 bilateral co-operation accord.
The French charity they worked for, Zoe's Ark, is facing a separate French investigation.
Hunger strike
Group leader Eric Breteau went on hunger strike while still in Chad. His lawyer says he is very weak, but he did arrive at the French hearing.
Chad map
All but one of the aid workers, nurse Nadia Merimi, were present in the courtroom.
The aid workers' actions sparked outrage in Chad.
Zoe's Ark insisted tribal leaders in Sudan had told them all the children were orphans from Darfur. It said it wanted to save the children's lives and was carrying out a medical evacuation - not an adoption operation.
In statements to police, the families said they had not been told their children were about to be taken abroad.
They claimed that the aid workers misled them into believing the youngsters - aged one to 10 - would be offered temporary local school places.
The Chadian government also accused the charity of "absconding without payment" of bills accrued in their attempt to fly the children out of the eastern town of Abeche.
In November seven Europeans arrested with the six Zoe's Ark workers flew home, accompanied by French President Nicolas Sarkozy.
Source: BBC
