Libya's eastern administration said the aid conference is slated for October 10, and will focus on presenting modern, rapid projects for the reconstruction of Derna.
The conference is in "response to the demands of residents of the stricken city of Derna and other towns that suffered damage" during the flooding, the statement added.
International aid groups estimate at least 10,000 people are missing from Libya's floods. The death toll stands at more than 3,300.
The International Organization for Migration Thursday said over 43,000 people have been displaced by the natural disaster.
A hurricane-strength storm hit Derna on September 10 and its heavy rains broke through two ageing dams upstream, resulting in the destruction of entire neighborhoods and thousands of people swept into the sea.
Libya remains split between a United Nations-backed government in Tripoli in the west, and the eastern government in the disaster-hit, backed by military leader Khalifa Haftar.