The 9 x 7in (23 x 18cm) black and red chalk drawing of the head of a middle-aged man was knocked down at €3.2m (£2.68m) – more than six times the €500,000-600,000 estimate – at Gestas Carrère, a small firm in Pau.
The auctioneers, who were assisted in the cataloguing by Paris Old Master drawing specialist Cabinet De Bayser, said the portrait will now enter an American collection.
The drawing was recently rediscovered in a private collection, its whereabouts unknown since July 1, 1833, when it was sold as part of the collection of Dutch banker and art collector Johann Goll van Franckenstein (1756-1821).
The bearded man depicted in the drawing appears in three major works completed by del Sarto in the 1520s. The theory persists that it may be a self-portrait.
The discovery in Pau represents a significant addition to the artist’s oeuvre. Less than 200 drawings by del Sarto survive, with fewer than 10 in private hands.
The last example on the market was the chalk head of Saint Joseph, a preparatory drawing for the Bracci altarpiece with subsidiary studies c.1526-27, that sold for a premium-inclusive £6.5m at Christie’s London in 2005.