Bus Éireann has signed a new five-year direct award contract with the National Transport Authority (NTA).
The contract, worth more than €800m, is for the delivery of public transport services across Ireland.
The company says in excess of 220 million journeys are to be provided over the course of the contract.
The new five-year contract begins on Sunday December 1st.
Bus Éireann chairman Aidan Murphy says: "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 adds: "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.
"Bus Éireann has delivered strong passenger growth in 2019, and we are delighted to have played our part in conjunction with the NTA by significantly growing usage of public transport."
And NTA chief executive officer Anne Graham says: "PSO bus routes provide a very important public service to communities all over Ireland as part of the Transport for Ireland (TFI) public transport network.
"Customers expect and deserve a safe, reliable and quality bus service and under this contract, we are challenging Bus Éireann to meet those expectations."