Commuters in parts of Dublin and Galway will see significant improvements on some of their busiest bus routes from today.
It comes as Bus Éireann were awarded a new five year contract worth more than €800m over five years.
The deal with the National Transport Authority will start today and includes the delivery of services for 218 routes nationally.
In excess of 220 million customer journeys will be provided over the course of the contract.
24-hour services on Dublin's 41 and 15 routes are among the changes.
There is also a new bus route linking Swords and Ashbourne.
Tim Gaston of the National Transport Authority said that there are also major improvements for Connemara in Co Galway.
"In Galway, we have additional morning and evening services running on the 424 which is the Galway services out to Connemara and to Lettermullan.
"And also, we have increased evening services running on the 419 which is the Galway-Oughterard/Clifden services," he said.
Bus Éireann chairman Aidan Murphy said: "Bus Éireann is very pleased to be awarded this new contract, which is a very strong recognition of the high standards of service we have delivered over the past five years.
"We are grateful that the NTA have entrusted us to continue delivering public transport services nationwide, and we look forward to our future positive collaboration."
Its chief executive officer Stephen Kent added: "We are very proud to be awarded this new contract by the NTA.
"It is a testament to all of our staff, who dedicate themselves in providing a safe, excellent and quality service to our customers.