He served as ambassador four times to the Holy See, thrice to Milan and once each to Naples, Hungary, France and the Empire.
[2] He was brought before the Avogadoria de Comun for his prove di nobiltà (confirmation of nobility), which usually took place around the age of eighteen, on 3 September 1445.
After Venice was placed under interdict by Pope Sixtus IV, Sebastiano was sent to Frederick II, Holy Roman Emperor, to defend the republic's actions.
[2] Sebastiano served a second stint as podestà of Verona, finishing the late Francesco Diedo's term in 1484.
[2] Some of Sebastiano's letters survive alongside those of Benedetto Trevisan in a collection from the period of his final Milanese embassy (1494–1495).
The collection is entitled Registrum litterarum magnificorum dominorum Sebastiani Baduario equitis et Benedicti Trivisano oratorum ad illustrissimum dominum ducem Mediolani ('register of letters of the magnificent lords Sebastiano Badoer, knight, and Benedetto Trevisan, orators to the most illustrious lord duke of Milan').
Letters to Sebastiano survive from Giovanni Michele Alberto da Carrara, Bernardino Gadolo [it], Marsilio Ficino and Marcantonio Sabellico.
[2] Despite these meagre survivals, Sebastiano's reputation as a humanist by the numerous references to his learning in contemporaries' writings.
In 1482, Nicoletto Vernia dedicated to Badoer his edition of Walter Burley's commentary on Aristotle's Physics.
[2] In 1496, Alessandro Benedetti dedicated his Diario de bello carolo to Sebastiano Badoer and Bernardo Contarini [it].
[1] Antonio Cittadini dedicated to Badoer his work on Averroes and Giorgio Valla his edition of Eusebius of Caesarea.