Nadal was the Olympic champion at Beijing in 2008 but missed the London Games with a knee injury four years later.
The 30-year-old is due to be Spain's flag-bearer at the opening ceremony in Rio on August 5 but still needs the go-ahead from the International Tennis Federation after he failed to meet qualifying criteria.
"Nadal's commitment is total and he will go to Rio to participate," said Alejandro Blanco, the president of the country's Olympic committee (COE).
Nadal is due to play singles and also the mixed doubles with French Open champion Garbine Muguruza at Rio.
However, he is still recovering from a left wrist injury which caused an early withdrawal from the French Open as well as forcing him to sit out Wimbledon.