The twins - named Hassan and Boubacar - were born in west Africa's Guinea in January, joined at the stomach.
Their mother said that neither doctors nor midwives were aware ahead of time that the twins would be conjoined, so the birth was natural, reported Le Figaro newspaper.
They are believed to be the only conjoined twins - also known as Siamese twins - ever to be born in Guinea.
(The twins' mother Fatoumata. Photo: Photo: La Chaîne de l'Espoir)
Upon hearing the news, a specialist team of surgeons from France visited the family in Africa, then flew them to the Necker specialist hospital in Paris for separation.
The operation was carried out under extreme secrecy at the hospital, and was funded by donations to the La Chaîne de l'Espoir charity, which was founded in France to help children in need around the world.
Surgeons knew the job wouldn't be an easy one, with examinations showing that the twins shared a liver and a 30 centimetre stretch of small intestine.
The team of four pediatric surgeons and three plastic surgeons, however, were confident the rare feat could be carried out successfully.
And indeed, they were correct. Mid last week, the two boys went under the knife in an operation that lasted nine-and-a-half hours.
Separating conjoined twins is a rare medical operation in France. The head surgeon in charge of the Guinea brother, Yves Aigrain, told Le Parisien newspaper that he had only had three similar jobs in his seven years at the hospital.