Azzo VI (1170 – November 1212), also known as Azzolino, was an Italian nobleman and condottiero. He held the title of Marquis of Este (marchio Eystensis) from the death of his father, Azzo V (1190) until his death.
He was heavily involved in the Guelph politics of Lombardy in the first decade of the 13th century, serving as podestà of Ferrara (1196, 1205, and 1208), Padua (1199), Verona (1206–1207), and Mantua (1207–1208 and 1210–1211).
In his capacity as a leading Guelph condottiero Azzo fought a prolonged war with Salinguerra Torelli. In 1205 he conquered and razed the castle of Fratta, residence of Salinguerra. His opponent responded by allying with Ezzelino II da Romano and drove Azzo away, but the next year (1206) he had reconquered Fratta, which he held until 1209.
When emperor Otto IV descended to Italy, he had Azzo and Salinguerra reconciled. However, after Salinguerra left the alliance, Azzo entered the league formed by pope Innocent III against the emperor. In 1208 the pope made him marquis of Ancona, while the people of Ferrara named him at the city's seignior.
In 1212 Azzo sided with the exiles from Vicenza in the war against Ezzelino, but the latter defeated him at Pontalto near Vicenza. Azzo took refuge in Verona, where he died in November of that year.
Azzo's first wife Elisa, a daughter of a count Aldobrandino, was dead by 1192. They had a son, Aldobrandino I, who succeeded his father in 1212 (who had a daughter, Beatrice d'Este, Queen of Hungary).