Businesses donated 14 million euro to more than 3,000 charity groups last year, it has been claimed.
A study showed employees also gave up 94,000 hours to volunteer for community organisations and raised 3 million euro through initiatives during 2009.
Business in the Community Ireland (BITCI), a network of Ireland's biggest companies which calculated the figures, said major firms and thousands of small businesses were doing great work in communities.
Tina Roche, BITCI chief executive, said: "This is the first time that the impact of businesses within society has been measured on such a scale.
"The support of business should not be underestimated and the need for such support will only grow in years to come as government funding is restricted.
"We hope that this is just the start of a process in capturing business impact."
Pat Carey, Minister for Community, Equality and Rural Affairs, said the business sector provided much-needed support across key areas such as education, health, and tackling disability and disadvantage.
"A wide range of social and community initiatives are only possible because of the partnerships that have been formed between businesses and not-for-profit organisations and communities," he said.
BITCI launched an interactive map to outline which parts of the country had benefited from community and volunteer organisations.
Mr Carey added: "The map demonstrates that a very significant number of companies are doing a huge amount of work in local communities throughout Ireland."