The number of people with dual citizenship, meanwhile, jumped by 87.4% compared to 2011
There has been a slight decrease in the number of non-Irish nationals living in Ireland, according to the latest Census results.
The CSO says it recorded 535,475 foreign nationals here on Census night last year - down 1.6% compared to 2011.
In contrast, the number of people with dual citizenship almost doubled - up 87.4% to 104,784 people.
Dublin City (91,876 non-nationals), Fingal (46,909) and Cork County (42,002) had the largest numbers of non-Irish national residents, while Leitrim (3,526) and Sligo (5,892) had the lowest.
Polish nationals were the largest group of non-nationals - 122,515 people - followed by British (103,113) and Lithuanian (36,552) nationals.
People from 12 countries - America, Brazil, France, Germany, India, Italy, Latvia, Lithuania, Poland, Romania, Spain and the UK - accounted for almost three-quarters of the non-nationals living here.
Galway was the most multicultural city proportionally, with 18.6% of its residents recorded as non-Irish.
In comparison, around 17% of Dublin City residents and 16% of Fingal residents were non-Irish nationals.
The figures also show that 612,018 residents here spoke a language other than Irish or English at home.
There were 96,497 non-national students (aged five and over) in the country, while non-Irish workers accounted for 14.9% of the workforce.
Irish-Americans, Irish-UK and Irish-Polish were the three largest groups of people with dual citizenship.
Deirdre Cullen, Senior Statistician with the CSO, explained: "This report gives a detailed insight into the many different nationalities living in Ireland, including their age profile, marital status, the languages they speak, and their educational and employment status.
"Non-Irish nationals and those with dual nationality are now well established in Irish society and communities throughout the country, and this report provides a wealth of information on their social and economic circumstances in April 2016.”