Mancini was a very precocious artist: he arrived in Naples in 1865, entering the Institute of Fine Arts when he was only twelve years old, and studied there under Filippo Palizzi and Morelli. His early works center around themes of everyday reality, like the sculptures of his friend Vincenzo Gemito. In 1872 Mancini exhibited two paintings at the Paris Salon and in his first trip to Paris in 1875 he met the Impressionists, a contact which pushed his art toward a more luminous, painterly style. He painted for the art dealer Goupil and worked also for Mesdag, the Dutch dealer and collector. In 1883, Mancini settled permanently in Rome; he lived in Frascati from 1912 until 1918 as guest in Villa Jacobini, owned by his patron Fernand du Chene de Vère.