The Great Mosque of Sivas was built in 1197 by Kizil Arslan under the rule of Seljuk prince Qutb al-din Malikshah. In plan the prayer hall is rectangular, thirty-one by fifty-one meters, with a large courtyard to the north that makes the entire mosque compound square. Originally, the courtyard could have been entered by doorways at the center of the northern wall and on the east and west walls adjacent to the prayer hall; only the eastern doorway is used today, as the others have been filled in with masonry. The prayer hall has two mihrabs on the exterior wall facing the courtyard; this outer prayer area has probably once covered by a roof. 

From the exterior the prayer hall appears long and low, owing to its flat earthen roof supported by wooden beams set on stone piers. The horizontal roof is interrupted by the brick minaret that rises at the southeastern corner of the mosque. The octagonal base of the minaret is decorated with a Kufic inscription made of turquoise tiles. It is thirteenth century in style, and may have been completed after the prayer hall. Access to the minaret steps is through a door at the eastern end of the qibla wall.

The prayer hall is entered from a central doorway. Inside, the space is divided by the stone piers into eleven north-south aisles and six east-west arcades. The mihrab is at the end of the center aisle; most of the other aisles have windows at either end. The remains of the stone mihrab indicate that it was once decorated with fine geometric patterns.