Praised as a painter, Lomazzo wrote about artistic practice and art theory after blindness compelled him to pursue a different professional path by 1571.

Other works by his hand include an elaborate dome with Glory of Angels for the Capella Foppa in San Marco in Milan, and the Fall of Simon Magus in the wall of the chapel.

His first work, Trattato dell'arte della pittura, scoltura et architettura (1584), is divided into seven books: Proportion, Motion, Color, Light, Perspective, Practice, History, and iconography related to classical and Christian subjects.

[6] Lomazzo's more abstract Idea del tempio della pittura ("The ideal temple of painting", 1590) describes the "four temperaments" theory of human nature and personality and contains explanations about of the role of individuality in judgment and artistic invention.

[citation needed] David Piper quotes[7] his influential views on portraiture: Emperors above all other Kings and Princes should be endowed with majesty, and have a noble and grave air which conforms to their station in life ... even though they be not so naturally in life.Giovanni Ambrogio Figino, Cristoforo Ciocca, Girolamo Ciocca[citation needed], and Pietro Martire Stresi[8] were his pupils.