|Born||18 May 1641|
|Died||27 December 1729|
|Known for||Italian noblewoman|
Olimpia Giustiniani (18 May 1641 – 27 December 1729) was an Italian noblewoman of the houses of Giustiniani and Barberini. She was the granddaughter of Olimpia Maidalchini, niece of Pope Innocent X and wife of Maffeo Barberini, Prince of Palestrina.
After the Wars of Castro, Pope Innocent X had instigated an investigation into the Barberini family and a number of them had been forced into exile in Paris. But several years later, Giustiniani's grandmother Olimpia Maidalchini realised her influence over the pope was waning. She set out to engineer a return of the Barberini to Rome, thus currying favour with a number of their family cardinals. The Barberini, too, were keen to return to Rome and were enthusiastic about Maidalchini's plan.
In 1653, Maidalchini decided that her 12-year-old granddaughter, Olimpia Giustiniani, would be a perfect match for 22-year-old Maffeo Barberini, son of Taddeo Barberini, future Prince of Palestrina and heir to the Barberini estate.
They had five children, including Francesco Barberini and Urbano Barberini. By marriage she became sister-in-law to both Cardinal Carlo Barberini and Lucrezia Barberini, who married Francesco I d'Este, Duke of Modena.