The Tokyo Olympic Games will start on 23 July, 2021 and run to 8 August after being postponed for a year because of the coronavirus pandemic.
The International Olympic Committee’s (IOC) executive board met on Monday to make the decision.
The Olympics will still be called Tokyo 2020 despite taking place in 2021.
The Paralympic Games, originally due to start on 24 August, 2020, will now take place between 24 August and 5 September, 2021.
IOC president Thomas Bach said: “I am confident that, working together with the Tokyo 2020 Organising Committee, the Tokyo Metropolitan Government, the Japanese Government and all our stakeholders, we can master this unprecedented challenge.
“Humankind currently finds itself in a dark tunnel. These Olympic Games Tokyo 2020 can be a light at the end of this tunnel.”
International Paralympic Committee president Andrew Parsons added: “When the Paralympic Games do take place in Tokyo next year, they will be an extra-special display of humanity uniting as one, a global celebration of human resilience and a sensational showcase of sport.
“With the Tokyo 2020 Paralympic Games 512 days away, the priority for all those involved in the Paralympic movement must be to focus on staying safe with their friends and family during this unprecedented and difficult time.”