The Abuja Football College products have both penned four-year contracts with the Italian club.
Umar (19) is a striker and Nura (18) is a right-back. Both players were on loan at Roma last season from Serie B side Spezia, who have now made their moves permanent for €2.5-million each.
Roma have also completed the permanent signing of Italy forward Stephan El Shaarawy from AC Milan for €13-million.
The 23-year-old has signed a four-year permanent contract with the Giallorossi after a successful six-month loan deal.