The unframed 2ft 4in (71cm) square oil on canvas sold for a hammer price of €1.85m (£1.63m) at an auction held by Christophe Joron-Derem at Drouot on December 19.
The price surpasses the previous recorded high of €720,000 (then £626,085) paid at Sotheby’s Paris in June 2014 for Gentileschi’s portrait of Mary Magdelene.
The newly discovered work, for which Eric Turquin was the expert specialist, is a significant addition to Gentileschi’s oeuvre. It takes the form of a self-portrait of the artist in the role of the female saint and is similar in composition and dimensions to her rendition of St Catherine now in the Uffizi in Florence.
It is dated to c.1614-16, corresponding to the artist’s Florentine period when her work was still influenced by that of her father, Orazio Gentileschi.