Al-Afdal Shahanshah was born in Acre, the son of Badr al-Jamali, the Armenian mamluk who had become Muslim.

Badr has served as vizier for the Fatimids in Cairo from 1074 until his death in 1094, when al-Afdal succeeds him.

Caliph Ma'ad al-Mustansir Billah dies soon afterwards, and al-Afdal appoints as caliph al-Musta'li, a child, instead of Musta'li's much older brother Nizar.

Al-Afdal claims that Imam Mustansir had changed his choice of successor upon his death bed, appointing his younger son (who is married to the daughter of Badr al-Jamali, the sister of al-Afdal Shahanshah).