[3] The Great Mosque of Sfax is not precisely date but assumed to be built around the same time, circa 849 AD, but it was extensively modified after the Aghlabid period.

[4][5] The sponsor of its construction was reputedly the qadi 'Ali ibn Aslam al-Jabanyani, a student of the Maliki scholar Imam Sahnun.

[7] In the 10th century the mosque was reduced in size by suppressing its western half, giving it a much narrower floor plan and leaving the minaret standing at its corner instead of at the middle of the courtyard's northern side, as was usual at the time.

[4] The unusually decorated exterior eastern façade of the mosque is also attributed to the Zirid period by multiple scholars, including Georges Marçais and Lucien Golvin.

[1][6]: 108 The mosque was enlarged in the 18th century, during the Beylik period, by re-extending the prayer hall to the west, giving it its present layout.

[1] were the architects of the mosque.As a result of this expansion, the mosque's surface area became similar to its hypothesized original size, but the courtyard remained small compared to the prayer hall.

[1] The architects in charge of this work were, Haj Sa'id al-Qatti, the chief mason, and the artist Tahar al-Manif, who is also named as the craftsman of the mihrab.

In the western section, the hypostyle naves run the whole length of the mosque, except for the slightly truncated corner where the present day street passes.

[6]: 73  The central mihrab of the mosque, dating to the 18th-century renovations, is fluted or grooved on the inside and is decorated with Kufic Arabic inscriptions.

[9]: 29  The wooden doors that grant entry from the narthex to the prayer hall were crafted by a master carpenter named Ahmed Sha'abuni.

The last tier at the summit is a thin lantern-like structure open on four sides, with engaged colonettes at its corners, and topped by a dome.

[6]: 109 The exceptional eastern exterior façade of the mosque is embellished with a series of decorative horseshoe arch-shaped niches or recesses above the doors and windows.

[1][6]: 108  In addition to the overall composition, another unusual feature is the reuse of a Byzantine marble panel with Christian votive themes set into the wall above one of the windows.

The panel is carved with an image of two peacocks facing each other (partly erased by chisel at some unknown date) against a background of foliate motifs and with a Greek inscription above.