This article argues that John Florio was the former owner and reader of a copy of Dante Alighieri’s Divina Commedia now held at the British Library (Shelfmark C.78.d.13, dated 1564). This discovery not only sheds new light on Florio’s engagement with Dante but also has the potential to resolve the long-standing mystery of Florio’s lost library, an enigma that has remained unresolved to this day. Through comparative analysis of the annotations with Florio’s known works and handwriting, this study reveals the working method of an Italian linguist actively engaging with Dante’s complex lexicon. These annotations reflect a deliberate effort to expand the English lexicon, as evidenced in his pioneering dictionaries, positioning him as a crucial mediator between Italian Renaissance literature and Elizabethan England. By situating Divina Commedia within Florio’s intellectual framework, this study reconsiders his influence on Shakespeare and highlights his lasting impact on the development of the English language.