The tests must be carried out by a healthcare provider within 24 hours of arrival to Saint Lucia and self-administered tests will not be accepted.
Unvaccinated travellers are still required to present proof of a negative PCR test taken up to five days prior to entering Saint Lucia and must stay in Covid-certified properties.
All travellers must register their information and upload test results online prior to travel.
Chief executive of the Saint Lucia Tourism Authority, Lorine Charles-St. Jules, said the Caribbean island has "continuously" evaluated its Covid-19 travel protocols.
"These major changes are good news for visitors and returning nationals as it means a simplified process, greater access to testing and a significant reduction in cost."