Petrarch’s two sonnets on Simone Martini’s portrait of Laura (Rvf 77 and 78) initiated a widely successful poetic genre in the sixteenth century: sonnets on portraits. Texts belonging to this genre often offered theoretical considerations on the issue of paragone between poetry and painting. Benedetto Varchi’s Due Lezzioni (1550) closely analyses this subject by building on Petrarch’s lyric poems and Triumphs. While Petrarch’s decisive impact on the Renaissance debate on ut pictura poësis has been widely emphasised, less attention has been devoted to his influence on portraiture, especially on the portraits by painter Agnolo Bronzino, a poet himself and a contributor to the paragone debate. This essay investigates the extent to which the intellectual dialogue between Varchi and Bronzino was inspired by Petrarch’s ideas on paragone, which he expressed in his vast production in Latin and in the vernacular.