Rousseff said 6,000 homes would be paid for by state and federal governments and the rest would be donated by a group of construction companies, the BBC reported.
The president said the country would also invest in flood prevention measures in the Rio de Janeiro region, where the flooding occurred.
About 540 people were missing.
The homes will be given to people living in shelters and to those being removed from areas considered unsafe following flooding and mudslides.
"Their pain is insurmountable and their loss has no price, but this initiative can improve the situation a little," Rousseff said.
The new residences will be built on public land.
Rousseff said the government will map out locations susceptible to flooding and landslides and make efforts to stop unauthorized building in dangerous areas.
Federal money will also be used to rebuild roads and bridges and to pay for hillside stabilization and drainage projects.