Fiadh has bumped Grace down the list to take the top spot for baby girls' names registered in 2021, while Jack remains the most popular name for boys.
Jack has been the most popular name registered with the Central Statistics Office for boys in Ireland every year since 2007, except for 2016 when James was the most popular choice
Of registrations for boys in 2021, the top five most popular names were Jack, Noah, James, Conor and Rían.
Fiadh claimed the top spot for girls for the first time, followed by Grace, Emily, Sophie and Éabha.
Grace, Emily and Sophie have been permanent fixtures in the top five names for baby girls every year since 2016.
Commenting on the trends in Irish baby names, CSO statistician, Gerard Dolan said: "Looking back 50 years ago to 1971, John, Michael, Patrick, David and James were the names most favoured by parents of newborn baby boys. There were 198 male newborns named John in 2021, compared with 2,654 in 1971.
"There were 198 male newborns named John in 2021, compared with 2,654 in 1971.
"Interestingly, not one of the top five names for girls in 2021 appeared in the top 100 names a half-century earlier.
"Mary, Catherine, Margaret, Fiona and Sinead were the most popular names for baby daughters in 1971, with 1,907 baby girls named Mary in that year."
In 2021, there were 424 baby girls named Fiadh, 22.2% of the number of girls given the name Mary (1,907) in 1971.
After only one new entrant into the top 100 names for boys in 2020, there were ten new entrants for 2021: Teddy, Daithí, Páidí, Jaxon, Brody, Ted, Hunter, Tadgh, Tiernan and Arlo.
The boy's name with the most growth in popularity in terms of rank between 2020 and 2021 was Ted, jumping 49 places from 139th place to 90th place.
There were three new entrants to the top 100 for girls: Indie, Ayla and Lottie.
Croía is the girl's name that has grown the most in popularity in 2021, jumping 43 places, rising from 95th place in 2020 to 52nd in 2021.
Mr Doolan added: "Some less common names for boys included Rome, Kobie, Thady, Saul and Eanna. Less popular girls' names included Sky, Princess, Valerie, Ophelia and Noelle."