The 'Hung Up' hitmaker, 55, and Rocco, whose father is Madonna's former spouse Guy Ritchie, toured the country which was left devastated by an earthquake three years ago.
The singer was there looking at the work done by the Haitian Relief Organisation, which is run by Penn, 53.
"I don't know if I called her or if it was one time that we ran into each other but, I said, 'Would you like to come down?'. She said she would. She came down with her son Rocco and it was great to have them down there," Penn said.