Illy started work in the family's coffee making firm illycaffè in 1977, which was founded by his grandfather in 1933.

Illy is the author of a book entitled Dal Caffe all'Espresso (From Coffeebeans to Espresso) published by Mondadori and translated into English, French and German.

Standing as an independent supported by a coalition which preceded Ulivo (the Olive Branch Party) and also by a civic list bearing his name, Illy has been elected twice — in 1993 and again in 1997 — as Mayor of Trieste.

He was awarded an honoris causa degree in political sciences at the University of Trieste after his "lectio doctoralis" on the topic of enlargement of Europe to the Eastern Countries.

When the direct election of the president was obtained, he kept his promise to the citizens of Trieste, and he ran as a candidate for the Friuli-Venezia Giulia Region supported by the Democratic Coalition Party (Intesa Democratica).