Gennari was baptised at Cento, a market-town near Bologna, and spent his youth in Bologna. Coming from a family of painters, he trained under his uncle, Guercino, who influenced his early style. When Guercino died, Benedetto and his brother Cesare took over direction of the studio. An admirer of the French king Louis XIV, Gennari travelled to France in March 1672 with his cousin Francesco Riva, and stayed for over sixteen months painting commissions for the nobility. His records indicate that he painted about fifteen pictures, including religious and mythological subjects and portraits.
He journeyed on to London in September 1674, presenting to the King his painting Diana and Endymion, which he had painted for the Duc de Richelieu but not delivered, fearing he would not be paid for it. He spent fourteen years in England as a court painter for Charles II and his successor James II, producing over a hundred pictures for Charles and another thirty-five for James. One of his early commissions was for a portrait of Queen Catherine, for whom he also painted altarpieces and other devotional subjects. Four large pictures of scenes from Ovid's Metamorphoses are at Hampton Court (Royal Collection). He also painted several erotic pictures for Charles II, such as Sleeping Shepherd (c.1682, Royal Collection).
When the papists were ordered from London in 1689, Gennari followed the Catholic court of James II into exile at Saint-Germain-en-Laye near Paris, producing another thirty pictures for the monarch. His biographer, Giampietro Zanotti, noted that, in his twenty years away from Italy, Gennari's style underwent such change that he appeared almost to be a northern painter. He returned to Bologna in 1692, and in 1709 he was a founder-member of the Bolognese Accademia Clementina.
Jane Turner (ed.), The Dictionary of Art, London and New York 1996, XII, pp.279-80
Dwight C. Miller, 'Benedetto Gennari's Career at the Courts of Charles II and James II and a Newly Discovered Portrait of James II', Apollo, vol.117, no.251, Jan. 1983, pp.24-9