The country's population rose by 55,900, or 1.1%, in the year to April, bringing the total number of people living here to an estimated 4.98 million, new figures from the Central Statistics Office show.
The CSO said the rise was due to positive net migration into the country and natural increase as the number of births were higher than the number of deaths.
The number of immigrants to the State in the year to April is estimated to be 85,400, while the number of emigrants from the State over the same period is estimated at 56,500.
Irish nationals accounted for 33.8% of those returning immigrants - the highest number of returning Irish nationals since 2007.
The CSO also said that the number of births was 58,300 while the number of deaths was 31,200, resulting in a natural increase of 27,100 in the year to April 2020.
It said this marked the lowest level of natural increase recorded since the 2001 population estimates.
Meanwhile, those aged 65 and over increased by 3.4% to 720,100 in the year to April. The CSO said this age group has increased by 14.3% since 2016 and now accounts for 14.5% of the total population.
Today's CSO figures also show that the Dublin region experienced the strongest growth in the year as its population grew by 22,100, or 1.6%.
The population of Dublin in April was estimated to be almost 1.42 million persons, equating to 28.5% of the total population.
Today's figures also show that 56,500 non-Irish nationals arrived to live here and 28,200 non-Irish nationals emigrated abroad in the year to April.
The number of non-Irish nationals living in Ireland increased from 622,700 persons in April last year to 644,400 persons in April of this year and they now account for 12.9% of the total population.
The CSO's James Hegarty said it should be noted that today's figures cover the 12 months to April 2020.
"Therefore, as much of the reference period predates the beginning of the Covid-19 pandemic, the impact on today's figures is limited and the majority of the impact can be expected to be seen in the 12 months to April 2021," he added.
