Diego Della Valle was born on 30 December 1953 in Sant'Elpidio a Mare, in the Marche, the elder son of Dorino Della Valle and grandson of Filippo, who had begun making shoes at home in the 1920s. He studied law at the University of Bologna (English Wikipedia says he graduated in 1975; Italian Wikipedia says he sat only a few exams), spent time in the United States studying marketing, and joined the family business in 1975.
He took over the company in 1978 (Italian Wikipedia says 1979), opened a Milan office and created a women's shoe line under his own name, persuading designers to use the shoes in their shows for free. He named the company J.P. Tod's in 1978, choosing a name from a Boston phone book to sound American to New York customers and, according to Italian Wikipedia, because it is pronounced the same way in every language; the "J.P." was dropped in 1999. The Gommino driving loafer, with a sole of 133 rubber pebbles, followed in 1979 (1978 in Italian Wikipedia), and the first handbag collection in 1980. He used early forms of influencer marketing; Hollywood stars and Diana, Princess of Wales, who inspired the D-bag, helped make the brand famous. Critics, among them Lapo Elkann in 2014, have long said the Gommino imitates The Original Car Shoe of 1963.
He became chief executive of Tod's S.p.A. in 1986. The group added Hogan and Fay, the latter based on firefighters' work jackets he saw in Maine; English Wikipedia dates Fay to 1986 and Hogan to 1988, while Italian Wikipedia puts Hogan in 1986. With his younger brother Andrea, who took over day-to-day running in the late 1990s, he built the Tod's Group, bought 60% of Roger Vivier in 1995 and listed the company in Milan in November 2000. The later sale of Roger Vivier from the family to Tod's drew accusations of self-dealing from minority shareholders and a long dispute with French tax authorities, which he lost in 2024. In 2011 Tod's funded the restoration of the Colosseum in a €25 million deal whose exclusive image rights were suspended after complaints.
Outside the company he revived Acqua di Parma with Luca di Montezemolo in 1993, has owned Schiaparelli since 2007, co-founded the rail operator NTV, and has sat on the boards of LVMH, Ferrari, Generali and BNL. He owned ACF Fiorentina from 2002 to 2019 and was convicted of sports fraud in the Calciopoli scandal, a conviction upheld in 2013 though the sentence lapsed under the statute of limitations. In 2024 the family took Tod's private with L Catterton, keeping 54%, and in September 2024 John Galantic replaced him as chief executive; he remains chairman.