He received his MD at the University of Padua in 1523, and subsequently practiced the profession in Siena, Rome, Trento and Gorizia, becoming personal doctor of Ferdinand II, Archduke of Austria in Prague and Ambras Castle and Maximilian II, Holy Roman Emperor in Vienna.
A careful student of botany, he described 100 new plants and coordinated the medical botany of his time in his Discorsi ("Commentaries") on the Materia Medica of Dioscorides. The first edition of Mattioli's work appeared in 1544 in Italian. There were several later editions in Italian and translations into Latin (Venice, 1554), Czech, (Prague, 1562), German (Prague, 1563) and French.
In addition to identifying the plants originally described by Dioscorides, Mattioli added descriptions of some plants not in Dioscorides and not of any known medical use, thus marking a transition from to the study of plants as a field of medicine to a study of interest in its own right. In addition, the woodcuts in Mattioli's work were of a high standard, allowing recognition of the plant even when the text was obscure. A noteworthy inclusion is an early variety of tomato,the first documented example of the vegetable being grown and eaten in Europe.