The day before the couple are due to tie the knot again in a religious wedding ceremony, Andrea and Tatiana were seen taking their ten-month-old son to the church of Saint Joseph for his baptism.
The proud parents were joined by their family and friends including Princess Caroline, Charlotte Casiraghi, Pierre Casiraghi and Princess Alexandra of Hanover.
Tatiana held her son, whose full name is Alexandre Andrea Stefano Casiraghi, close as the pair entered the church. Given the snowy weather, 30-year-old Tatiana sported in a warm black coat, a patterned monochrome dress, black tights and boots, while Sacha was dressed all in white.
Close behind Tatiana was her husband Andrea, dressed in a smart grey suit and a red tie, while proud grandmother Princess Caroline sported maroon trousers and a grey and white fur-lined coat for the special occasion.
Elsewhere in the snowy Swiss ski resort, preparations for Andrea and Tatiana nuptials are well underway.
The past couple of days has seen the arrival of the couple's guests including, fashion heiress Margherita Missoni, Olympia Scarry and Fabiola Beracasa.
Charlotte Casiraghi's ex-boyfriend Alex Dellal was also spotted in the picturesque town, accompanied by his fiancée Elisa Sednaoui and their five-month-old son, Jack.
The church where Andrea and Tatiana will say 'I do' has been given some special additions, and large flower-adorned trees we seen being delivered on Friday.
A sign erected outside the pretty church of Saint Joseph reads that the venue is hosting a wedding between the hours of 11am and 9pm.