Dressed in a white shirt and black jacket, King Juan Carlos's youngest daughter nodded to reporters as she left the court in Palma on the holiday island of Majorca after being questioned for seven hours.
Cristina was questioned over allegations that she was complicit in tax-dodging and money laundering in a courtroom overlooked by a portrait of her own father, Juan Carlos, 76, who is the head of state.
Long thought untouchable as a royal, Cristina, 48, is in the centre of the scandal over allegedly fraudulent business dealings by her husband, former Olympic handball player Inaki Urdangarin.
Cristina is the first direct member of the Spanish royal family in history to appear in a court as a suspect.
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"Everything has been cleared. The questioning has shown how the princess is innocent of all the accusations made against her," another of her lawyers, Jesus Maria Silva, told reporters.
The hearing follows more than two years of mounting anger against the elite in a Spain battered by recession.
Near the court on a sunny winter's day, scores of pro-republican protesters rallied, held back by police barriers.
"It seems the privileges they have aren't enough for them -- they have to do something that really annoys the people," said Mateo Castellanos, 61, who travelled hundreds of miles from the mainland to protest.
"A large part of the country is suffering hardship and a lot of people don't have enough to feed their children."
Majorca, where for decades Cristina's family sunbathed and sailed yachts in the summer, is now the centre of a scandal that has turned much of the public against them and raised doubts over the very future of the monarchy.