The 24-year-old was part of the Cameroon squad during the Africa Cup of Nations in Equatorial Guinea, when he suffered the injury setback.
N'Koulou had two fragments of cartilage removed during the operation and is now set for an extended spell on the sidelines, with Marseille targeting a potential return ahead of their top-of-the-table clash with PSG on April 5.
"On Monday morning, Nicolas N'Koulou was operated by Dr. Jean-Pierre Franceschi due to patellar cartilage damage in his left knee, contracted during the Africa Cup of Nations in Equatorial Guinea," the club said on Tuesday.
"The surgeon removed two fragments of cartilage and practiced articular lavage. No action has been practiced on cartilage itself."
N'Koulou has made 17 Ligue 1 appearances this season for Marcelo Bielsa's side, who are third, two points behind champions PSG and four adrift of leaders Lyon.
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