Blue helmets, working with local officials, helped rescue at least 330 families from Les Cayes, Torbeck, Chantal and Arniquet, according to the UN peacekeeping mission in Haiti (MINUSTAH).
Those rescued join hundreds of others who have sought shelter as rising waters engulf or damage their homes.
Several major rivers in the region have overrun their banks and much of downtown Les Cayes is under water, with more rain forecast for later this week.
MINUSTAH said it remains on alert to assist authorities across the affected region in case they are need for further rescues or the distribution of aid.
The UN Office for the Coordination of Humanitarian Affairs (OCHA) reported on Tuesday that at least two people have been reported missing since the heavy rains began, and there are fears that the floods could lead to fresh outbreaks of cholera.
Haiti has been hit hard by cholera over the past year, with nearly 6,500 people dying from the disease. But the death rate had been declining recently before the floods.