feni sadar upazila on the north, Companiganj (Noakhali) upazila on the south, Mirsharai upazila on the east, Companiganj and Daganbhuiyan upazilas on the west.

Sonagazi thana was established in 1920 and was turned into an upazila in 1983. The upazila consists of 9 union parishads, 94 mouzas and 93 villages.

Sonagazi Upazila is located in Feni District. Upazilla(s)/Thana(s) in Feni are Chhagalnaiya Upazila, Daganbhuiyan Upazila, Feni Sadar Upazila, Parshuram Upazila, Phulgazi Upazila, Sonagazi Upazila.