Diaz was born in Bordeaux, the child of refugees from Spain.  Soon after his birth his father seemed to have deserted the family and left for England.  His mother, existing by teaching languages, made her way from Burgundy to Paris.  As a small child, Diaz was bitten by a snake while walking in the countryside and consequently lost a leg.  By the time he was ten years old he was also orphaned, and given over to the care of a priest, presumably in Paris.

By the age of 15, Diaz was apprenticed as a printer and porcelain decorator, working under an uncle of Jules Dupré.  By 1830, having by now given up the porcelain decorating, he was painting avidly.  In 1831, he exhibited for the first time in the Salon with a painting titled Scène d’Amour, which received very good critical reviews.

Diaz first visited Barbizon in 1835 and from then on spent most summers there.  His paintings were either pure landscape or imaginative romantic historical or figurative pieces, many having backgrounds of forest scenery.  He became financially successful and won many medals.  Much of his works were done for dealers, the trade and commissions from important aristocrats for portraits.  Because of his commercial success he was able and generous enough to help his needy friends, Troyon, Rousseau, and Millet in Barbizon.  In 1849 he was elected a member of the Salon Jury, and in 1851, having previously won many medals, he received the Legion d’Honneur.  Diaz reached the height of his fame in 1855 at L’Exposition Universelle.   Diaz exhibited regularly in the French provinces where he received maximum exposure. 

During the latter part of his life, his delight was to take what he called his “morning exercise,” which was hunting through the antique stores and the dealers looking for reminders of his earlier days, for example at one time he discovered a painting done by him in his early days, which he had sold for 25 Francs.  He was delighted to pay the dealer 3000 francs, and rushed home with it and hung it over his bed.  In another one story, a dealer describes how Diaz discovered a little painting of a baby in a crib with a mother bending over it.  As it turned out, the painting was by Diaz himself; it portrayed his wife and child that had died.  Diaz had sold it when he needed the money, but it had great sentimental value to him and he begged to buy it back. 

Diaz died of lung disease, nursed by his wife.  After his death, Jules Dupré, a lifelong friend and pallbearer at his funeral, wrote of Diaz, “the sun has lost one of its most beautiful rays.”

Museum collections include: