The French-Luxembourgish performance artist received the fine for posing nude in front of the grotto entrance in Lourdes in 2018.
The sentence was issued on Thursday morning by the correctional tribunal of Tarbes in the south of France.
A fine of €2,000, with €1,000 on parole, was issued for what was determined as an act of sexual exhibition. De Robertis' lawyer Marie Dosé reacted straight away by announcing that she would appeal the verdict on the grounds that this incident was her client's first misdemeanour.
On 31 August 2018, De Robertis got undressed and put her hands together above her head while only covered with a blue veil in front of the entry of the grotto, where according to catholic scripture, the Virgin Mary appeared in front of Bernadette Soubirous in 1858. People at the scene intervened to cover the artist and called the police.
The 36-year-old explained at the time that her performance tried to capture the spirit of both Mary and Mary Magdalene in the same body. She had previously gained attention for similar acts, most notably in 2017 when she uncovered herself in front of the Mona Lisa.