The Tokyo Olympics will take place between July 23 and August 8 next year.
The International Olympic Committee confirmed the news on Monday, which followed a meeting of the Tokyo 2020 organising committee.
A decision to postpone the Olympic and Paralympic Games was taken last week by the IOC and the Japanese government because of the accelerating threat posed by the coronavirus pandemic.
A statement from the IOC also confirmed the new dates for the Paralympic Games, which will now take place on August 24 to September 5.
"These new dates give the health authorities and all involved in the organisation of the Games the maximum time to deal with the constantly changing landscape and the disruption caused by the COVID-19 pandemic," the statement read.
"The new dates, exactly one year after those originally planned for 2020 also have the added benefit that any disruption that the postponement will cause to the international sports calendar can be kept to a minimum, in the interests of the athletes and the international federations.
"Additionally, they will provide sufficient time to finish the qualification process. The same heat mitigation measures as planned for 2020 will be implemented."
Speaking today, Chef de Mission for Team Ireland in Tokyo, Tricia Heberle welcomed the clarification of a date,
"Now the athletes have a start date for the Games, they can work with their Performance Directors and coaches to start mapping out preparations. Importantly for athletes and sport, the next information we need clarity on are any changes to qualification and the rescheduling of qualification events. This will take some time, so in the short term the focus remains the same, stay healthy and safe over the coming months.
"The priority now is for everyone to following the government guidelines to protect Ireland and the rest of the world against further spread of this virus. A July 2021 start means that we have plenty of time to reactivate preparatory plans and for athletes currently in modified training or on a break of sorts, this period of time can still allow some positive impact on performance.
"If we are smart, this enforced break can make Team Ireland even better."