The woman contacted store personnel for help and was taken to the supermarket infirmary, a room normally used as a rest area for unwell shoppers, according to a report in the Le Parisien daily.
"She told me she was having contractions, so I asked her how long she had left to her due date, she replied that she was at full term," a security officer at the Auchan de La Défense supermarket told the newspaper.
Supermarket staff called the emergency services, who arrived just in time to assist in the birth of a little baby boy.
The woman and child were then taken by ambulance to the Notre-Dame de Bon Secours maternity clinic in Paris' 14th administrative district.
In the course of all the birthing commotion the woman lost her purse which was later recovered by store staff. The woman's seven-year-old son who had accompanied her to the store was furthermore entrusted into the care of supermarket security staff.
"He stayed with us, we had lunch together, it was great fun," a security officer told the newspaper.
The young boy was subsequently handed over to police and later reunited with his father later in the afternoon.
Supermarket staff confirmed that Wednesday stands to be a day to remember.
"It was a nice event, a change from the routine," one remarked.