The wearing of face coverings in shops, supermarkets and shopping centres will become mandatory from Monday.
The decision, originally announced several weeks ago, will be implemented in the same way it was on public transport.
Taoiseach Micheal Martin said: "As we have seen with face coverings on public transport and the many other requests that have been made for citizens over the course of the pandemic.
"When people are given a clear direction they follow it."
The news was confirmed by Mr Martin at a press briefing from Dublin Castle, where he announced Ireland will not move to phase four of the reopening roadmap on Monday.
Pubs, hotel bars, nightclubs and casinos will not be allowed to reopen next week.
The limit on both indoor and outdoor gatherings will not be increased, meaning fans will not be able to attend GAA or League of Ireland matches.
The decision to hold off on moving to the next phase of Ireland's roadmap comes after a large spike in new cases over the past week.
The measures announced today will be reviewed again in three weeks time.
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