The sporting competition, featuring athletes from 206 nations, gets underway with an opening ceremony at the city’s Maracana Stadium at midnight BST.
More than 500,000 tourists are expected to attend the games, which will showcase 28 sports over August 5-21.
Competitions will take place across 32 venues in Rio, with a number of football matches also scheduled to be played in the cities of Belo Horizonte, Brasilia, Manaus, Salvador and Sao Paulo.
The games will be the first Olympics to be held in South America, with the Rio 2016 Paralympic Games following in September.
Build-up to the event has been dominated in recent months with concerns over the spread of the Zika virus in Brazil and issues surrounding security and infrastructure in Rio.
