He was also called "El-İmâdî", because his family was from İmâdiyye, "Abū s-Su"ūd" or "Hoca Çelebi". In the 1530s, Ebussuud served as judge in Bursa, Istanbul and Rumelia, where he brought local laws into conformity with Islamic law (sharia). Sultan Suleiman the Magnificent promoted him to Grand Mufti – supreme judge and highest official – in 1545, an office Ebussuud held until his death and which he brought to the peak of its power.
Together with Suleiman, the "Lawgiver", Ebussuud reorganized Ottoman jurisprudence and brought it under tighter governmental control, creating a legal framework joining sharia and the Ottoman administrative code (qānūn).
While the previously prevailing opinion held that judges were free to interpret sharia, the law that even the ruler was subject to, Ebussuud instituted a framework in which the judicial power was derived from the Sultan"s and which compelled judges to follow the Sultan"s qānūn-nāmes, "law-letters", in their application of the law. In addition to his judicial reforms, Ebussuud is also remembered for the great variety of advisory opinions (fatwās) he issued.
His opinions allowing Karagöz plays and the consumption of coffee, a novelty at the time, are particularly celebrated. In the television series Muhteşem Yüzyıl, Ebussuud Efendi is played by Turkish actor Tuncel Kurtiz.