Nathalie De Mey, 32, was convicted on Thursday by an all-female jury in the southwestern French city of Carcassonne for the February 2nd, 2011, murder.
Murder of a minor is normally punishable by a life sentence, but De Mey's term was reduced because she was deemed to have had a temporary loss of judgement.
On Wednesday when De Mey was asked why she did not choose a "more violent" method to kill the infant, she replied: "I didn't want to hurt him."
Her lawyer Pierre Calvet's argument of temporary loss of judgement was confirmed by a psychiatric assessment.
De Mey, who has two living daughters, said she had gone on several alcoholic binges during her pregnancy.
"When I realised I was pregnant, I tried to get help... but it was too late," she testified.
She recounted how she gave birth to the child over a toilet.
"When the baby came out, I caught him by the head so he wouldn't fall in the water, then I cut the cord with scissors."
Hours later, she said, she placed the baby, swaddled in a blanket, in the freezer.
The dead baby was discovered by the father of De Mey's two daughters three months later.
Her lawyer said before the trial that De Mey had been afraid of admitting to her estranged companion that the third child was not his.