Aleksandra Kuligowska, a volunteer at a hospital run by the Caritas Catholic charity, was abducted on Friday with a Mexican colleague.
"She is safe and healthy, which I have told those close to her by telephone. I thank local forces and our French allies for their actions," Polish foreign affairs minister Radoslaw Sikorski said on X, formerly Twitter.
Poland's defence minister Wladyslaw Kosiniak-Kamysz on X addressed his "warmest thanks to French defence minister (Sebastien) Lecornu and to the French soldiers, thanks to whom the Polish woman was released."
He said she would soon return to Poland.
Ildjima Abdraman, the governor of the southern Tandjile province, insisted that local forces from the central African country had rescued Kuligowska.
Abdraman said Kuligowska had been "freed by our defence and security forces" after she was located in Kimri canton.
"When the helicopter flew overhead the kidnappers came out to try to shoot down the helicopter, leaving the hostage alone," Abdraman added.
"Meanwhile our ground troops advanced, they managed to rescue the hostage. All the kidnappers were killed. There were three of them."
Kuligowska was taken to the capital N'Djamena by helicopter, Abdraman said.
A spokesperson for the French forces stationed in the Sahel told AFP that Chadian forces carried out the rescue but refused to say what part French soldiers played.
Chad has been an integral part of the G5 Sahel regional organisation created in 2014 to combat jihadism in the sub-Saharan region.
However, the organisation looks set to dissolve after the withdrawal of Mali, Burkina Faso and Niger following military coups in those countries in recent years.
All three have expelled French troops from their countries.
Frequent kidnappings
Sikorski shared a video of him talking by telephone, apparently to Kuligowski's relatives, telling them: "Your prayers have been heard, your daughter will soon be home."
Chadian and French forces based in the central African state had been looking for Kuligowska, who was seized with a Mexican colleague from the St Michel hospital in Dono Manga, southern Chad.
No group claimed responsibility for the kidnapping and the Mexican national was later abandoned.
Armed bandits frequently kidnap Chadians for ransom in the region, about 400 kilometers (250 miles) south of the capital N'Djamena.
Two armed men accompanying a fake patient went to the hospital to carry out the abduction, according to Abdraman.
The two doctors were taken away on motorbikes, the official added. Security forces gave chase and the Mexican doctor was left at the roadside but the group kept Kuligowska.
WARSAW - A Polish doctor kidnapped in southern Chad last week has been released following a joint operation between French and Chadian forces, authorities said on Tuesday.