The Sanjak of Gümülcine (Ottoman Turkish: Sancak-i Gümülcine, Greek: Υποδιοίκησις Γκιουμουλτζίνας, Bulgarian: Гюмюрджински санджак) was a second-level province (sanjak) of the Ottoman Empire in Thrace, forming part of the Adrianople Vilayet. Its capital was Gümülcine, modern Komotini in Greece.