A former British colony that gained independence in 1966, Barbados has maintained a formal link with the British monarchy as have some other countries that were once part of the British empire.
"The time has come to fully leave our colonial past behind," said Barbados Governor-General Sandra Mason, delivering a speech on behalf of the country's Prime Minister Mia Mottley.
"Barbadians want a Barbadian head of state. This is the ultimate statement of confidence in who we are and what we are capable of achieving. Hence, Barbados will take the next logical step toward full sovereignty and become a Republic by the time we celebrate our 55th Anniversary of Independence."
That anniversary will come in November 2021.
Buckingham Palace said the issue was a matter for the people of Barbados. Britain's Foreign Office said the decision was one for Barbados to take.
In 1998, a Barbados constitutional review commission recommended republican status, and in 2015 then prime minister Freundel Stuart said "we have to move from a monarchical system to a republican form of government in the very near future".
Most Caribbean countries have kept formal links with the monarchy after achieving independence.
Barbados would join Trinidad and Tobago, Dominica and Guyana if it proceeds with its plan to become a republic. Jamaica has also flagged such a transition, with Prime Minister Andrew Holness saying it's a priority of his government.