The Tokyo Olympic Games will start on 23 July, 2021 and will run to 8 August after it was postponed for a year because of the coronavirus pandemic.
The executive board met on Monday to make a decision after the 2020 Games were moved from this summer.
The Olympics will still be called Tokyo 2020 despite taking place in 2021.
The Paralympic Games, originally due to start on 25 August, 2020, will now take place between 24 August and 5 September, 2021.
The decision to postpone both events was taken to protect the health of the athletes and everyone involved, and to support the containment of the Covid-19 virus.
The new dates also took into consideration the rest of the global sports calendar after the men’s football European Championship was postponed to the summer of 2021.
Organiser hope the delay will allow sufficient time to finish the qualification process which will follow the same mitigation measures planned for 2020.
On 24 March, Japan’s Prime Minister Abe Shinzo said the Games would be held in their “complete form” and no later than summer 2021.