Sent at an early age to study at the University of Perugia, he promptly returned to Ferrara, complaining of poor health and bad treatment at the hands of his fellow students.
They resorted to the law; but Duke Alfonso II d'Este, to avoid scandal, appointed an arbiter.
This time Alessandro left Italy, accompanying Guido Bentivoglio to Brussels; but he was compelled to hasten back to meet the lawsuit his father had set in motion against him in his absence.
Alessandro Guarini seems at one time to have been professor of literae humaniores in Ferrara, and Secretary to the Duke.
Besides minor verses, which appear never to have been collected, he published a tragicomedy, Bradamante Gelosa (Ferrara, 1616), and three prose works: a Trattato del vero, e real fondamento della catolica fede (1635), an Apologia di Cesare (ibid., 1632), and Il farnetico savio overo il Tasso (ibid., 1610), a dialogue on literary theory between the poet Cesare Caporali and Torquato Tasso, whom Alessandro had known since his childhood.