The Sultan said the hijab is a sign of decency and mode of dressing for any woman.
He said the Nigerian constitution allows the use of the hijab.
The victim, Firdaus Amasa, had refused to to remove her hijab at the Nigerian Law School - the school decided to punish her by not calling her to the bar.
This sparked outrage on social media at the weekend, with many Nigerians criticising the school for the action.
Speaking at the fifth national convention of Muslim Public Affairs Center (MPAC) on Saturday, December 16, 2017, the Sultan said the hijab is a sign of decency and mode of dressing for any woman.
"Why will a legal school refuse our sister's induction into the judiciary simply because she was wearing hijab?" Sa'ad, who was represented by the Waziri of Katsina, Sanni Abubakar Lugga, asked.
He added, "Is the Law School saying they are above National Judicial Council (NJC), they are above the Nigerian constitution, and they are above these three senior courts?
"His Eminence wonders why hijab has now become a controversial issue. Hijab simply means decent dressing by females. So why should decent dressing be a problem? The hijab is not just an Arabic word. In English it means decent dressing.
"His Eminence has asked Nigerians to reflect and see that this is not only an Islamic mode of dressing but a Christian mode of dressing.
"It is also a Judaism mode of dressing and it is a dressing for every decent woman. It is a dressing for any woman who wants to preserve her chastity in public."
According to the affected law student, Amusa Firdaus, she deliberately stood her ground not remove the hijab to give her Muslim sisters the right to express their constitutional rights.