Joanna of Austria has been vindicated as one of the Habsburg women who played the most important political role during the period in which she acted as governor in the absence of her father, Charles V, and her brother (1554-1559). Previous works have succeeded in reconstructing her religious and cultural profile and her role as a patron of the arts, as well as in deepening her biography. In this article we focus from a literary point of view on her biography by Juan Carrillo and on her correspondence with the almiral Doria and the ambassador for Genoa during her regency, in order to analyse how her imagen as ideal model for female governor was createad and how she exercised a real “missive reginality”, how her self-representation as a ruler is perceived in the letters and how she dealt with the conflicts of the period, as the discovery of Lutheran groups or the death of her relatives.