In 1727, Blanchet won second prize at the Prix de Rome and thereafter he settled in Rome, where he gained the protection of the Duc of Saint-Aignan who at that time was French Ambassador to the Holy See. For the Duc de Saint-Aignan, in 1732, Blanchet painted a set of four overdoors with allegorical subjects.
Blanchet’s reputation was based primarily on his portrait paintings, mostly commissioned by British and French visitors coming to Rome during their Grand Tour. Blanchet served also as court portraitist of the Stuart family who lived in exile in Rome and one of his most famous paintings is the Portrait of Prince Charles Edward Stuart (Windsor, Royal Collection).
The elegant and soft style marked by luminous colours gained success and made Blanchet the favourite painter of British travellers before the rise of Pompeo Batoni.