Qilla Saifullah, Killa Saifullah or Saifullah Qilla (fort of Saifullah Khan) is a district in the north west of Balochistan province of Pakistan.

Qilla Saifullah became a district on 14 December 1988 and is named after Saifullah Khan, who was from the Mirdadzai (Khodadzai) tribe of Kakar Sunzerkhail. Qilla Saifullah used to be part of Zhob District and known as Upper Zhob sub-division. In 2006 Kashatoo sub-tehsil of Zhob District was transferred to Qilla Saifullah district with a new name, Badinai.
 

After the inclusion of Badinai sub-tehsil, (whose area is not known) in Qilla Saifullah District, the district was re-organised as far as administrative division is concerned. At present the district is divided into two sub-divisions: Qilla Saifullah and Muslim Bagh. Qilla Saifullah sub-division comprises one tehsil (Qilla Saifullah) and one sub-tehsil (Badinai). Qilla Saifullah tehsil is further sub-divided into 2 Qanungo circles and then into 5 patwar circles.

The entire Badinai sub-tehsil is a Qanungo circle as well as patwar circle. Muslim Bagh sub-division comprises Muslim Bagh tehsil and Loiband sub-tehsil. The entire Muslim Bagh tehsil is one Qanungo circle, further sub-divided into 4 patwar circles.

The Loiband sub-tehsil consists of one qanungo circle and is sub-divided into 2 patwar circles Over 99% of the people of the area are Muslims. The population of Qilla Abdullah district is estimated to be over 350,000 in 2005. The vast majority of the population of Qilla Saifullah is Pakhtun.