[Claude Debussy, half-length portrait, seated, facing left] / portrait by J.E. Blanche ; photo by Em. Crevaux, Paris.

Although Blanche received some instruction in painting from Henri Gervex, he may be regarded as self-taught. He became a very successful portrait painter, with a style derived from 18th-century English painters such as Thomas Gainsborough as well as Édouard Manet and John Singer Sargent. He worked in London, where he spent time from 1870 on, as well as Paris, where he exhibited at the Salon and the Société Nationale des Beaux-Arts. One of his closest friends was Marcel Proust, who helped edit several of Blanche's publications. He also knew Henry James and is mentioned in Gertrude Stein's The Autobiography of Alice B. Toklas. In Paris, at the Académie Vitti, he took a portraiture class with Canada’s first female battlefield artist Mary Riter Hamilton. In 1902, Jacques-Émile Blanche took over the direction of the Académie de La Palette, where he would remain director until 1911. He taught at the Académie Vitti in 1903. Among the painter's most famous works are portraits of his father, Marcel Proust (private collection, Paris), the poet Pierre Louÿs, the Thaulow family (Musée d'Orsay, Paris), Aubrey Beardsley (National Portrait Gallery, London), and Yvette Guilbert and the infamous beauty Virginia Oldoini, Countess of Castiglione whom his father had treated for mental illness. Others he painted included James Joyce, Julia Stephen, Edgar Degas, Claude Debussy, Auguste Rodin, Colette, Thomas Hardy, John Singer Sargent, Charles Conder, Percy Grainger, and Tamara Karsavina as Stravinsky's Firebird.