Her husband, however, Inaki Urdangarin, was given a jail sentence of six years and three months for siphoning off millions of euros between 2004 and 2006 from a foundation he headed in the island of Majorca.
The 51-year-old princess was the first member of Spain's royal family to face criminal charges since the monarchy's restoration in 1975.
"We must acquit and we are acquitting Cristina Federica... of tax fraud, of which she was accused," the court said.
The case, heard in Palma, sullied the reputation of the royal household and became a symbol of the elite's perceived corruption. The scandal broke in 2011 amid Spain's deepest economic crisis in decades.
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Princess Cristina was facing up to eight years in prison if convicted of fraud over her 49-year-old husband's work with the non-profit Noos Institute sports foundation.
Urdangarin, a former Olympic handball medallist was charged with the more serious crimes of embezzlement, influence peddling, forgery and money laundering.
After her 1997 fairytale marriage to Urdangarin, Princess Cristina was in the celebrity spotlight and won praise for having a salaried job.
But eventually, people began to raise eyebrows at the couple's lavish lifestyle.
In 2004 they purchased a 1,200-square-metre (13,000-square-foot) house for six million euros (USD 6.3 million) in Barcelona, with centre-right daily El Mundo asking: "Where is the money coming from?"
When Spain was hit especially hard by the global financial crisis, the so-called Noos scandal further fanned public anger against the ruling class.
Cristina's husband Urdangarin has consistently claimed he never made any decisions without the royal family's knowledge.
Since the scandal erupted, the pair have been excluded from all of the family's official public appearances.
After today's ruling was announced, Cristina's lawyer Miquel Roca said she was "satisfied" with the verdict but saddened by her husband's jail sentence.
"She was satisfied but also ... Pained to see her husband convicted. She believes his conviction is unjust, because she has always believed -- and still believes -- that he is innocent," Roca told reporters in Barcelona.