Andrea Casiraghi and Tatiana Santo Domingo are to wed on 31 August, according to French publication Paris Match.
It's been reported that the couple, who have been engaged for a year and together for eight, have set the date for a wedding in Monaco and that the invitations have already been sent out – although the Palace has not yet confirmed that the nuptials will take place.
Andrea is the son of Princess Caroline and her late husband Stefano Casiraghi. The young royal and his fiancée met through his sister Charlotte, who turned 27 on Saturday after the two young women attended the same school in Fontainebleau, near Paris.
Charlotte is also thought to be expecting a child of her own.
Good news keeps coming for the principality's reigning Grimaldi clan. The couple welcomed a baby boy on 31 March at London's Portland Hospital, whom they have named Sacha.
She appears to be in the second trimester of pregnancy, although there has been no official confirmation.
Much like Kate Middleton, Tatiana exudes humility and has perfected the art of being a discreet yet supportive consort. Her low-key approach is something the Monegasque royals – Caroline in particular – appreciate. Since establishing their relationship, the couple have stayed away from the media spotlight.
Once his parents are married, Sacha will be included in the line of succession to the Monegasque throne after his grandmother Caroline and his father.
Tatiana is the granddaughter of the late Colombian mega-mogul Julio Santo Domingo, and is set to inherit an estimated $6bn fortune which she will share with her younger brother Julio Mario Santo Domingo III.Despite her vast wealth she has worked hard to establish ethical fashion brand Muzungu Sisters, which she co-founded with business partner Dana Alikhani, daughter of the late Iranian businessman Hossein Alikhani.