Bhanga upazila on the north, Kotalipara and Gopalganj Sadar upazilas on the south, Madaripur Sadar and Shibchar upazilas on the east, Muksudpur and Gopalganj Sadar upazilas on the west.

Rajoir as an informal thana was established in 1914 and was upgraded as a complete thana in 1982 which was turned into an upazila in 1983. The upazila consists of 10 union parishads, 93 mouzas and 177 villages.

Rajoir Upazila is located in Madaripur District. Upazilla(s)/Thana(s) in Madaripur are Kalkini Upazila, Madaripur Sadar Upazila, Rajoir Upazila, Shibchar Upazila.