The failure of the Ottoman army in the Siege of Vienna in 1683 led to a 16-year conflict with the Holy League States. This situation required the adoption of financial measures to sustain the war. The most notable of these financial measures, known as the "Imdad-ı seferiye", was the attempt to generate revenue from Waqfs. Accordingly, half of the annual revenue of Waqf employees was demanded in 1688 and 1694. The most significant part of this empire-wide policy was implemented in Istanbul, since the revenue generated from Waqfs in Istanbul exceeded the empire's revenue generated from Waqfs in Anatolia and Rumelia. This study aims to examine the contribution of waqfs in Istanbul to war financing at the end of the 17th century. In this context, it first focuses on the economic dimension of the waqfs in Istanbul, highlighting the significance of large-budget waqfs such as Selatin, Hanım Sultan, and Pasha waqfs, which employed a considerable number of staff. The study also addresses the vezaif akçesi collected from the waqfs in Istanbul in 1684 and 1694, arguing that the revenue from the vezaif akçe was primarily obtained from high-budget waqfs. Finally, it is noted that in 1698 the Ottoman state once again requested financial aid from the waqfs in Istanbul. However, the amount collected was not obtained through the vezaif akçesi method, but rather by means of the tevziat method.