Giovanni Panerai (1825–1897) was the Florentine watchmaker from whom Officine Panerai dates its history. In 1860 he opened his first shop on the Ponte alle Grazie in Florence, a small business combining precision mechanics and watchmaking. Panerai describes it as at once a watch shop, a workshop and the city's first watchmaking school.
The bridge's reconstruction from 1876 forced the business to move between several Florentine addresses. After Giovanni's death the firm passed to his grandson Guido Panerai (1873–1934), son of his eldest son Leon Francesco. Guido gave the shop the name Orologeria Svizzera, made it the agent for leading Swiss watch brands, above all Rolex, and in 1926 moved it to its best-known address, inside the archbishop's palace in Piazza San Giovanni, opposite the Baptistery and the cathedral. He also took over his wife's family's mechanical workshop and, from the 1910s, supplied precision instruments to the Royal Italian Navy.
That naval work, carried on by Guido's son Giuseppe, produced the inventions for which the name is known. The Radiomir luminous compound was recorded in a French patent addendum of 23 March 1916. A 1935 Navy order led to the Ref. 2533 prototype and to the Ref. 3646 Radiomir dive watch, and the Luminor name was registered in 1949. The crown-protecting bridge was patented in 1956. In 1972, after Giuseppe's death, the engineer Dino Zei took over and the firm became Officine Panerai. It entered the civilian market in 1993, was bought by the Vendôme group (now Richemont) in 1997, and today makes its watches in Neuchâtel, Switzerland, while the Piazza San Giovanni shop remains its historic boutique.
Little is recorded about Giovanni Panerai's own life beyond the founding of the shop; most of what bears his name was the work of his descendants.
Sources for his personal life are thin. German Wikipedia's claim that a great-grandson took over in 1890 conflicts with other sources, which name his grandson Guido, and Casadi follows them.