Bakerganj upazila on the north, Barguna Sadar upazila on the south, the Rajganj river and Patuakhali Sadar upazila on the east, Betagi upazila on the west.

Mirzaganj thana was established in 1812 and was turned into an upazila in 1983. It consists of 6 union parishads, 68 mouzas and 72 villages.

Mirzaganj Upazila is located in Patuakhali District. Upazilla(s)/Thana(s) in Patuakhali are Bauphal Upazila, Dashmina Upazila, Galachipa Upazila, Kalapara Upazila, Mirzaganj Upazila, Patuakhali Sadar Upazila.

Single domed Shahi Mosque at Masjidbaria (1710s).