The Spanish princess arrived at the courthouse in Palma de Mallorca at 9:45, saying "good morning" to the waiting photographers and journalists and telling them she was feeling "well".
Cristina's lawyer said she was calm ahead of Saturday's proceedings, but added that he did not yet know if she would respond to all of the judge's questions.
HELLO!'s sister magazine HOLA! have reported that the counsel made a brief statement during a break in Cristina's testimony, saying that she was responding evasively on many issues, often saying "I do not know, no answer."
During her testimony, the mother-of-four is also believed to have said that she has "a lot of confidence" in her husband Iñaki Urdangarin's innocence.
King Juan Carlos' daughter is being questioned over her involvement in the embezzlement case investigating her husband.
Iñaki is suspected of having overcharged local authorities for organising sporting and tourism events and Cristina's involvement and knowledge of events is now coming under scrutiny.
The Infanta is being asked about Aizoon, the company she co-owned with Iñaki, including spending within company over the period 2006-2008.
Last year, Cristina was ordered to appear in court as part of the investigation, but the decision was overturned after the regional court of Mallorca found insufficient evidence to link her to her husband's business affairs.
During the time since the scandal broke it has been business as usual for the Spanish royal, who has been seen taking her children to school in Geneva, where she is now based, and going to work at her office as normal.