Dublin to Belfast journey times on the Enterprise train service are set to be reduced to under two hours.
Funding of €165m has been awarded to the service by PEACEPLUS and will support a "major transformation" of the service, which is a joint venture between Iarnród Éireann and Translink.
The Enterprise train service has been in operation for 75 years and recorded more than one million journeys in 2022.
With the new funding, the entire Enterprise fleet will be replaced with brand new trains by the end of this decade.
The existing four train sets will be replaced by eight new and modern trains, which Iarnród Éireann say will reduce journey times and improve accessibility and passenger experience.
The new trains are expected to support goals of net zero carbon emissions as both jurisdictions move towards a fully electrified cross-border rail corridor.
The PEACEPLUS Programme is managed by the Special EU Programmes Body which is designed to promote peace and prosperity across Northern Ireland and border counties.
It has a value of €1.14bn to be delivered over the next five years.
Recently, the Government announced €25m in funding to provide an hourly Enterprise train service under the Shared Island initiative.
Jim Meade, the Chief Executive of Iarnród Éireann said that the new fleet will enable more people than ever to travel sustainably along the Enterprise route and "contribute to our economy, society and environment".
Chris Conway, the CEO of Translink, said that the Enterprise represents a "tremendous opportunity for growth".
He said that around 3.3 million people live within a 40-mile commute from the Belfast to Dublin rail corridor, and this is projected to grow to more than four million by 2030.
"Development of the Enterprise service is key to building competitiveness and in the creation of close links and communications between the people and communities living and working in and between the two main cities on the corridor.
"We hope that this encourages more people to leave their cars at home and use public transport," said Mr Conway.
