Rescue teams are continuing to search for survivors on Ilha Grande.
Officials say the Sankay Lodge was full that when the mudslide hit. About 40 guests, including children, were ringing in the New Year.
There are few details about those who died. Authorities said no foreigners were known to be among them.
Witnesses said the houses and the resort had been hit by a piece of the hillside measuring some 300m across.
"It was a deafening noise, I've never heard anything like it - a loud thunder that wouldn't stop," Felipe Gomes Martins, a neighbour of the hotel, told the Brazilian news website G1.
Other landslides in Angra dos Reis killed 13 people on Friday.
On Thursday at least 19 people died as heavy rains triggered mudslides in Rio de Janeiro state.
Local authorities have declared three days of mourning.
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