But her husband, Iñaki Urdangarin, a former Olympic handball medallist was jailed for six years and told to pay a €512,000 fine. He was charged with the more serious crimes of embezzlement, influence peddling, forgery and money laundering between 2004 and 2006.
Urdangarin can file an appeal but may be taken into custody soon as the prosecutor is considering whether to request his imprisonment, a judicial source said.
The 51-year-old princess was the first Spanish royal to face criminal charges since the monarchy's 1975 restoration.
A court in Palma, on the Mediterranean island of Majorca, issued the ruling at noon (11:00 GMT). The couple were not in court for the verdict, which can be appealed.
“We must acquit and we are acquitting Cristina Federica… of tax fraud, of which she was accused,” said the court.
However, Princess Cristina was ordered to pay a fine of 265,000 euros ($282,000) because she had benefited from her husband's wrongdoing.
The case, heard in Palma, has sullied the reputation of the royal household and become a symbol of perceived corruption among Spain's elites.
The scandal broke in 2011, just as the country was going through a deep economic crisis.
Princess Cristina could have faced eight years in prison if she had been convicted of fraud over her 49-year-old husband's work with the non-profit Noos Institute sports foundation.
The couple, who have been married since 1997 and have four children together, went on trial last year along with 15 others, including former government minister Jaume Matas.
After her 1997 fairytale marriage to Urdangarin, Princess Cristina became a treasure of the celebrity press 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 ($6.3 million) in Barcelona, with centre-right daily El Mundo asking: “Where is the money coming from?”
Urdangarin has grown visibly thinner over five months of hearings that have garnered huge media interest, while the princess has largely stayed mute in court.
'Equality of all citizens?'
When Spain was hit especially hard by the global financial crisis, the so-called Noos scandal further fanned public anger against the ruling class.
It soured the last years of the reign of Felipe's father Juan Carlos, who gave up the throne in June 2014 after 39 years, hoping his son could freshen up the image of the monarchy.
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 Friday'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.
The judgement, he added, acts as proof of “the equality of all citizens before the law”.
The royal family did not comment on the ruling, though the place expressed its “greatest respect for the independence of the judiciary”.
King Felipe VI on Friday morning smiled as he opened an art exhibition in Madrid.
“No one is above the law,” said a spokesman of Prime Minister Mariano Rajoy's conservative government on Friday.
Spanish media said the couple learned of the ruling, which was delivered in absentia, in Geneva, where they have lived since 2013 with their children.
By Laurence Boutreux