At midnight on October 23, Olympian Dame Mary Peters will switch on the new high power digital TV transmission service in Northern Ireland, bringing to an end 50 years of analogue television.
This will mark the final stage of the five-year, £630 million project to turn off analogue TV signals in the UK and boost reception of Freeview to households.
The first analogue channels will switch off in Northern ireland on October 10, and then 13 days later Peters will be joined at Belfast's Divis broadcast transmission station by John Cresswell, the chief executive of transmission firm Arqiva, for the final switch-off ceremony.
"The switchover to digital TV is a momentous step for the broadcast industry and will promise viewers more channels to choose from and a better viewing experience than ever before," pentathlon hero Peters said.
"It's a very fitting end to what has been a phenomenal year for Britain. Not only have the Olympic and Paralympic celebrations shown the British and Irish people at their very best, but it's a reminder to the world of the outstanding reputation which British broadcasting upholds."
The Lord Mayor of Belfast, Alderman Gavin Robinson said: "Northern Ireland is proud to be completing the final leg of the UK's TV switchover and we're looking forward to bringing what has been a successful project to an end.
"The switchover will make a huge difference for everyone across Belfast and Northern Ireland, providing vital services and more choice to homes in the area."
The main stations at Divis, Brougher Mountain, Limavady and 43 relay transmitters across Northern Ireland will all switch to a new high-power digital system for Freeview, reaching 650,000 homes across the country.
More than 200,000 viewers will be able to watch Freeview and Freeview HD for the first time after the switch, as this will boost the power of digital TV in the region by ten times.
The final switchover in Northern Ireland is the result of five years of work constructing seven new multiplexes and upgrading three main transmission masts at Divis, Limavady and Brougher Mountain to digital.
Marking the historic moment, Holmes will present the first simultaneous live broadcast from UTV - the ITV licence holder in Northern Ireland - and BBC on the evening of October 23.
The programme will include "familiar faces" from local and network television and feature archive clips, interviews and a "few surprises".
"The completion of DSO in October will signal the end of what is a truly magnificent achievement for Arqiva and our Freeview partners, alongside Digital UK and Ofcom," Creswell said.
"In only five years, we have transformed this vital public service and built a modern platform for transmitting the best of British TV into over 20 million homes across the UK.
"Along with the launch of Youview, DSO, by providing digital television across the UK, cements 2012 as a landmark year in British broadcasting keeping free-to-air viewing for consumers, at its core."
Alongside boosting the choice of subscription-free television in the UK, the completion of the digital TV switchover also frees up airwaves for deployment of high speed 4G mobile broadband services across Britain.
Ofcom will host a major auction of the 800Mhz spectrum previously used for analogue television later in the year. The UK's major mobile operators will roll out 4G services, capable of speeds up to ten times faster than 3G, will in summer 2013 under a recently-accelerated timetable.
> Final analogue TV channels switched off in England
> London bids farewell to analogue TV - feature