Mr Varadkar said the decision would give the public “reason to hope” but warned it was not a “cause for celebration”, as many restrictions will still remain in place.
“We have a long way to go yet. There will be bumps in the road and we have to keep our guard up,” the Irish prime minister said on Friday.
“If all goes well, we will enter a new phase of reopening our country every three weeks.”
From Monday, small groups of up to four people will be allowed to meet outside, so long as they keep two metres apart, and people who are involved in mainly outdoor work, such as those in construction and gardening, will be allowed to return to their jobs.
Garden centres, hardware stores, farmers’ markets, opticians and mechanics will also be able to reopen.
Mr Varadkar said the decision to move to phase one of the five-stage plan came following advice from the National Public Health and Emergency Team (NPHET), a group of scientific experts who have been advising the Irish government on Covid-19.
The next review will take place on 5 June, but the Irish PM warned that the public would have to continue following government guidelines in order to move to the next stage.
“Everything is provisional and reversible, and our progress depends on us all continuing to do what we have been doing,” he said.
“As the restrictions ease and we come into contact with more people, the opportunity for the virus to spread increases.
“So, self-discipline and personal responsibility will become more important, not less.”
The Taoiseach also urged the public to wear face coverings when using busy public transport or in an enclosed indoor public area — although this will not be a legal requirement.
On Friday, Tony Holohan, Ireland’s chief medical officer, warned coverings were “not magic shields” and insisted hand washing remained key to slow the spread of the disease.
“The evidence is not very strong in relation to the value of face coverings and we have evidence that with this disease, hand transmission is key,” Dr Holohan said.
“It is not a magic bullet for this disease and that has to be understood.
“Hand washing has to be maintained — we don’t want the message to get out that people do not have to wash their hands or social distance.”
Mr Varadkar also confirmed on Friday that horse racing would be able to resume behind closed doors and without spectators from 8 June.
Additional reporting by PA
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