A Queen's University Belfast (QUB) study has found that people who are breastfed as babies go on to earn 10% more by the time they are 50.
The study looked at 9000 people and found a significant financial benefit for those who are breastfed in infancy.
Research found that those who were breastfed had an average weekly household income of £708, compared to £588 for those who were not.
When the figures were adjusted to consider socio-economic background the different was found to be 10%.
Breastfeeding is believed to improve brain development and reduce the risk of illness.
The UK and Ireland have some of the lowest levels of breastfeeding in the world with many mothers preferring to use formula.
Just 0.5% of children in the UK are breastfed until the age of 12 months, the lowest level in the world.
The NHS recommends that women breastfeed their babies until they are at least six months old.
The Queen's study has suggested introducing public programmes to encourage more mothers to breast feed.
Study leader and QUB lecturer Dr Mark McGovern told the Daily Mail that breastfeeding has both health and financial benefits.
"Our initial results from the study suggest that a 10 percentage point increase in the number of breastfed babies in Northern Ireland [alone] each year could generate around £100million in additional lifetime earnings, of which around £20million could be expected to be collected in the form of tax revenue, which could be partly used for public health campaigns," he said.
"Our concluding results so far in the study show if more babies are breastfed there are likely to be substantial economic returns to the resources invested in these public health campaigns, and women and children could also benefit through improvements in health, cognitive ability, and greater earnings potential."