Some 350 million euro is to be invested by the Government and private enterprise in a final push to prevent a rural-urban digital divide.
Communications Minister Pat Rabbitte said bringing high-speed broadband to every home in the country is as important for jobs and society as electricity has been for the last 60 years.
The commitment is to provide the fastest fibre optic-style internet, 70-100 Megabits per second (Mbps), to more than half the population by 2015.
A fifth of homes and businesses, mostly those further from exchanges or in less populated areas, can expect standard broadband speeds of at least 40Mbps over the same period. This could increase to 35% of homes around smaller towns and villages.
The Government said that some of the 175 million euro it puts up will go towards guaranteeing speeds of at least 30Mbps for every remaining home and business in the country, no matter how rural or remote.
"Despite the pressure on government finances, we will invest public funds so as to make sure more thinly populated areas are not left behind. Internet connectivity is now as important for both employment and society as electricity has been for the last 60 years," Mr Rabbitte said. The plan will surpass the requirements for internet access under European rules, the Government said.
Separately, a report out on Thursday highlights the lack of home internet usage. Last year, six out of 10 homes which have an over-65 heading the household did not have web access. If the pensioner lived alone, the rate rises to 79%, according to Census 2011.
The revised broadband plan is born out of the report of the Next Generation Broadband Taskforce, published last May, which included chief executives of the six main telecoms service providers in Ireland.
Sean Murphy, Chambers Ireland deputy chief executive, said the investment is good news for business. "Business needs top quality broadband to reduce costs, be more productive, sustain employment and grow new markets," he said.
Mr Rabbitte said state funding is required as Ireland's population is more broadly dispersed than that of many other countries, limiting the regions where broadband expansion is commercially viable. "Notwithstanding the constraints imposed on the exchequer at present, government will intervene where, but only where, it is evident that the market will not deliver," he said.