Households in the Republic have £3,300 more disposable income annually than those in Northern Ireland, new research shows.
This equates to a 12% gap after accounting for price differences in both areas.
Life expectancy is also now 1.4 years longer in the south, according to the Economic and Social Research Institute (ESRI).
The Sunday Times reports that, across almost all indicators, standards of living were better in the Republic than in Northern Ireland.
Despite a perception that the NHS in Northern Ireland is superior to the Republic's Health Service Executive (HSE), researchers found little difference between them, with the south having more doctors in relation to its population size.
Co-author on the study, Adele Bergin, expressed surprise at this finding and said she believed it was caused by regional disparities across the NHS.
"Within the UK, the NHS in Northern Ireland is quite a poor performer. A person in Northern Ireland is at least 40 times as likely as someone in Wales to wait more than a year for care - and Wales is otherwise the worst performer in the UK," she said.
The ESRI study, published in Irish Studies in International Affairs, was conducted due to an increased focus on north-south comparisons, amid growing speculation about the possibility of a referendum on a united Ireland.
"Central to many cross-border issues and to any future border poll debate is an understanding of differences in living standards," the report concluded.
Using data from 2017, the researchers found that disposable household income was €3,800 (around £3,300) higher in the Republic than in Northern Ireland.
Relative poverty levels were "substantially lower" in the Republic, suggesting that the tax and welfare system there was more effective "in mitigating household poverty risk".
The researchers also found "stark differences" in engagement with education, which was higher in the south across all age groups. Northern Ireland had almost twice the rate of early school leavers.
In 2005, life expectancy in the Republic overtook that of Northern Ireland. Girls born south of the border in 2018 were expected to live 1.5 years longer, while boys also had a greater life expectancy by 1.4 years.
In 2018, life expectancy for 65-year-olds was half a year less in Northern Ireland.
In 2019, the Republic had 5% unemployment compared to just 2.7% in Northern Ireland.
"This is not entirely surprising as the sectoral composition of employment in Northern Ireland, and higher dependence on public sector employment, results in more stable employment and unemployment rates," researchers concluded.
University of Ulster economist Dr Esmond Birnie said there were some interesting statistics in the paper, "but some caution is in order."
"Regarding the provision of health care North and South they're entirely correct to note the appalling waiting lists here in NI. However, access (whether free at point of use as in the NHS model) is also important.
"An earlier paper (2019) by A Bergin (one of the authors of this report) noted only 32% of people in the Republic have access to 'free' care," Dr Birnie said.