The 10-month-old will be modelling designer swimwear on the cover of the Dolores Cortes US catalogue and star in the designer's 2013 DC Kids ads.
Her proud mum, Miami TV host Cecilia Elizalde said that her daughter 'teaches us much more than we will ever teach her'.
And in a statement about its decision to choose Valentine, Cortes said: "People with Down Syndrome are just as beautiful and deserve the same opportunities. I'm thrilled to have Valentina modelling for us."