The app, based on a Nintendo title that debuted 20 years ago, uses GPS and mapping capabilities in smartphones to let players roam the real world to find "PokeStops" stocked with supplies and hunt cartoon monsters to capture and train for battles.
"Hello Nintendo! There are 23 days until the Rio 2016 Olympic Games. Everybody's coming. You should come on down too," Mayor Eduardo Paes said on Facebook Wednesday, with the welcoming hashtag #PokemonGoNoBrasil (Pokemon Go in Brazil).
Some, like Paes, think people might enjoy hunting around the city's landmarks like Copacabana beach.
Half a million foreign tourists are expected in Rio for South America's first Olympics from August 5-21.
Ex-supermodel Gisele Bundchen will be in her native Brazil to host the opening ceremony.