The European monarch, 51, and her husband King Felipe, 56, have appointed María Dolores Ocaña Madrid to the important position, breaking tradition in the royal household.
Queen Letizia of Spain and her husband King Felipe looked sombre in navy blue and black as they paid their respects to the king s cousin at the mass at Castrense Cathedral in Madrid.
The Princess of Orange, 20, will attend her first ever state banquet in the Netherlands next week as her parents host the King and Queen of Spain, Dutch media reports.
Queen Letizia cut an elegant figure as she joined husband King Felipe VI at an arts award ceremony in Cadiz to present the Gold Medal of Merit In Fine Arts 2022 on Wednesday.