This article attempts to analyze the activities of senators from Royal Prussia and Warmia in the Senate during the reign of Władysław IV Vasa. The publication contains information on the representation of both secular and clerical senators at the Sejm of the Polish-Lithuanian Commonwealth. It discusses their participation in Sejm sessions and their activities during parliamentary debates, including participation in senatorial votes and work in committees. The analysis shows that these senators did not stand out in terms of their activity compared to other crown dignitaries participating in the Sejm. However, they were able to speak on matters concerning the provinces they represented and constituted a secondary link in the parliamentary structure of Władysław IV Vasa.