The speech watched by millions on TV is the most important national address by Spanish kings.
Cristina is the first royal family member ordered to trial since the monarchy was restored in 1975.
She is accused of benefiting from an alleged scheme by her husband that put embezzled funds into a company owned by the couple.
Cristina's lawyers say she is innocent and will appeal the trial order for her, her Olympic handball medalist turned businessman husband, Inaki Urdangarin, and 15 others.