The vestararius was the manager of the medieval Roman Curia office of the vestiarium (cf. the Byzantine imperial wardrobe and treasury, the vestiarion), responsible for the management of papal finances as well as the papal wardrobe. The vestiarium is mentioned as the papal treasury as early as the seventh century, during the period of Byzantine cultural hegemony in the West called the "Byzantine Papacy", but the vestararius itself is attested to only from the eighth century.
Along with the highest financial officers arcarius and the sacellarius, the vestararius was one of the three most important staff officials of the Lateran Palace (the palatini). By the ninth century the vestararius was a member of the papal household second only to the seven judges, while the other two offices figured among the "seven judges of the palace" who constituted the core of the papal court. While the other offices were responsible for the collection and dispensation of papal assets, respectively, the vestararius was responsible for guarding the wealth, possibly depositing in the wardrobe along with the papal vestiments. The vestararius was also responsible for the written financial archives and accounts, and may have received and distributed some sums independently of the other offices.
By 813, the vestararius was seated beside the pope in the Palace in giving judgement and in 875 was sent as an embassy to the Holy Roman Emperor.Theophylact I, Count of Tusculum, who for all intents and purposes ran the temporal affairs of the papacy during the saeculum obscurum of the first half of the tenth century, was a holder of the office of vestararius. His wife, Theodora, held the extraordinary position of vestararissa.