Kiss already broadcasts to 14 cities across the UK from its analogue base in London to digital markets including Birmingham, Manchester, Glasgow and Northern Ireland.
The new venture, EG Digital, will expand Kiss's potential audience in the UK by a further 9m potential listeners to 73% of the population who have access to digital radio, according to research from Emap's digital division.
Listeners in areas such as Bristol, Swindon and Wolverhampton will be able to tune into Kiss on GWR's digital audio broadcast network, NOWdigital.
Emap Performance chief executive Tim Schoonmaker, said: "In the analogue world, Kiss is the number one station for 14- to 24-year-olds in London. Together with distribution on Emap multiplexes, the joint venture increases Kiss's digital radio coverage to 73% of the population."
Simon Ward, director of digital and new media at GWR, said: "This partnership ensures we offer our listeners a top-quality brand and gives GWR the opportunity to be part of that.
"Powerful brands such as Kiss will only help to switch listeners over to digital radio. In this respect, we are delighted to be working alongside Emap Performance."
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