Aer Lingus and Emerald Airlines said they will start operating Aer Lingus Regional flights in March - 10 months ahead of schedule.
The Aer Lingus Regional flights, operated under a franchise agreement by Emerald Airlines, will begin on March 17.
Emerald Airlines plans to fly over 340 flights per week across 11 routes from March.
It said that high-frequency routes, including Dublin-Edinburgh and Dublin-Glasgow, will be served up to four times a day.
Today's announcement also sees the re-establishment of services to regional points across the UK, including Newquay, Cornwall, Exeter and Isle of Man.
Further route announcements will be made in the coming weeks.
Over 60 UK-US routes on the Aer Lingus network will also connect via Dublin Airport, including connections from UK regional airports to New York, Los Angeles, Boston and Seattle.
Start-up carrier Emerald Airlines was granted its Air Operator Certificate (AOC) in September, which paved the way for it to run regional services on behalf of Aer Lingus.
Lynne Embleton, CEO of Aer Lingus, said today is about "opportunities".
"Opportunities for our UK customers to connect with ease to Aer Lingus flights to North America and to take advantage of the US pre-clearance facility. Opportunities for customers across UK and Ireland as we develop the Aer Lingus regional network. And opportunities for the Irish economy and Irish aviation as we expand our hub at Dublin," the CEO said.
"It has been a pleasure to work with the team at Emerald Airlines to accelerate this partnership and start operations 10 months ahead of the original schedule. We are all looking forward to welcoming our customers on-board Aer Lingus Regional services, operated by Emerald Airlines," she added.
Conor McCarthy, CEO of Emerald Airlines, said the airline will start operations under its franchise agreement with Aer Lingus well ahead of plan in line with the recovering customer demand.
"This announcement is a great boost for connectivity from Ireland to the UK including cities such as Edinburgh, Glasgow, Newcastle, Bristol and Leeds. Emerald Airlines will be offering a high-frequency schedule with convenient flight timings to facilitate both business and leisure passengers," Mr McCarthy added.
Emerald has also established an airline company in Northern Ireland (Emerald Airlines UK Ltd) and has applied to the UK CAA for a UK AOC and Operating Licence.
"We are very confident that this will result in long-term connectivity being maintained across the Irish Sea and will boost business and leisure travel between Northern Ireland and Britain," the airline's CEO said.
"We have already reached a long-term commercial agreement with George Best Belfast City Airport and look forward to connecting Belfast to many cities in the UK as soon as possible in 2022. Further details, routes and launch dates in relation to the Belfast operation will be announced in the New Year," he added.
