The fifth-century abbess -- who is one of the country's three patron saints along with St. Patrick and St. Columba -- founded several monasteries of nuns. Her Feb. 1 feast day will become the new holiday; many Irish people mark that date as the traditional first day of spring.
Bishop Denis Nulty of Kildare and Leighlin, where St. Brigid founded her largest monastic settlement, had backed calls for the female saint to be honored on the civil calendar.
The new holiday, on which all public offices will close, will be in addition to St. Patrick's Day, which falls on March 17 and is also a public holiday.
This year, St. Patrick's Day will have an extra holiday March 18 as a special "thank you" to front-line health care workers for their work during the COVID-19 pandemic.
The government also announced Jan. 19 that all health care workers would receive a one-time, tax-free bonus of 1,000 euros (US$1,134) for their work during the pandemic.
It comes as health officials in Ireland are expected to announce a lifting of all COVID-19 restrictions and phase in a return to normal over the next nine weeks as rates of infection continue to fall. Ireland has the highest vaccination rate in Europe.