The spokeswoman said the death was a "suspected suicide".
Queen Maxima of the Netherlands, seen here with her husband, King Willem-Alexander, in 2017, was close to her sister, who was godmother to her third child, Princess Ariane.
The queen and her sister are native Argentinians.
She was a civil servant who had been working for the Argentinian government since 2016, in an office that oversees social policies.
As a result of Inés Zorreguieta's sudden death, Queen Maxima has canceled her upcoming events.
Inés Zorreguieta reportedly died of apparent suicide at her home in Argentina. "I wish them all the strength necessary to carry this terrible loss together and I trust that they will get the peace and space for that".More news: Amazon unveils Fire TV Cube, a streaming box with Alexa for $119
Máxima said in a reaction that she is "very shocked and very upset" by the news, the RVD said.
Her father, Jorge Horacio Zorreguieta, died previous year in Buenos Aires aged 89. "And I trust that they will get the peace and space for that".
He had served as agriculture minister during Argentina's brutal military dictatorship - a link that caused some controversy in the Netherlands, and led to a debate in the Dutch parliament, before his daughter married the crown prince.
Between 2009 and 2011 she worked at the United Nations headquarters of Panama but returned to Argentina in 2012 after a breakup.
If you or someone you know is having suicidal thoughts, help is available.