The veteran economist, who stepped down last year as deputy executive secretary of the UN's Economic Commission for Africa, is due to be formally selected on August 20.
"The leaders of the Alliance for Freedom and Change have fully agreed to nominate Abdalla Hamdok," one of the protest umbrella's leaders said, asking not to be named, Presstv Reported.
Another senior member of the protest movement confirmed to AFP that they had chosen Hamdok.
The protest umbrella and a ruling military council agreed an outline power sharing accord on July 17, ahead of a landmark deal paving the way for civilian rule that is meant to be signed on Saturday.
The military council came to power by toppling long-time president Omar al-Bashir in April on the back of months of protests, but demonstrations had continued as the Alliance for Freedom and Change demanded the generals step aside.
The compromise -- after it was agreed in principle by the two sides earlier this month -- mandates the protest umbrella to choose a prime minister to preside over Sudan's political transition.
The sovereign council will be formed on Sunday, according to the agreed-upon schedule, after which the Transitional Military Council will be dissolved. The appointment of the prime minister is scheduled to take place on Tuesday.
The opposition alliance will also nominate former judge and human rights activist Mohamed Alhafiz Mahmoud as public prosecutor, opposition sources said, and Abdelqadir Mohamed Ahmed as head of the judiciary.