Bauer Media houses more than 50 radio station, including Magic and Kiss, which last quarter had an average weekly reach of 13.3 million, according to the Rajar figures for Q3 2010.
The decision by the second biggest commercial radio company in the UK to join the Radioplayer, alongside UTV, is a significant vote of confidence for the new service, as it already has a successful, profitable radio player service of its own up and running.
Iain Clasper, development director at Bauer Radio, said: "Bauer's radio online growth strategy and the new Radioplayer launch complement each other perfectly. The big win for the radio industry in general is getting radio onto new devices which will further drive audience engagement, so this is an exciting moment for all of us."
Other radio stations set to join Radioplayer next week include Folder Media's Fun Kids, digital only station Planet Rock and Isle of Man-based Manx Radio.
Michael Hill, managing director of Radioplayer, told more than 150 media executives this morning that the way the digital device has been created so it can easily be embedded within individual station websites, meant it had a significant reach from day one.
He predicted around three million listeners would use Radioplayer in its first week.
The UK Radioplayer, the first online player to allow listeners to search across commercial and BBC stations, launched with 157 radio stations from the BBC, Global Radio, GMG Radio, Absolute Radio and Brighton's Juice 107.2. It is available to all radio stations with an Ofcom licence, including community and student stations.
Each version of the vertical pop-out Radioplayer has a common search function enabling listeners to search for radio stations by station, genres, geographic location and artist.
The players also have a common "My Stations" feature that allows users to save their favourite stations. The same saved stations will appear in whatever version of the player is opened.
The stations are then able to modify the rest of the player and the commercial stations will use some of the space for an advert and in the future hope to be able to match visual ads with the audio ads being played on the station.
Ashley Tabor, founder and executive president of Global Group, said: "Visual ads are something that we want to do and it is something we are already talking to our customers about. They love the simplicity of the player."
There are plans to try to extend Radioplayer onto smartphones and tablet devices and Tim Davie, head of audio and music at the BBC, said there has been a lot of interest from radio industries in other countries.
Davie said the Radioplayer was a "quiet breakthrough", which will prove to be "good news for listeners and good news for people who like radio".
Hill said he wanted the radio industry and manufactures to look at whether it would be possible to create a product which combined FM, DAB and online in a single player. "Who knows where it could go," he said.
Radioplayer's search facility, which will be refined and expanded over the coming months, means listeners searching for content inside the BBC’s player will receive results from the commercial industry, and vice versa.
Scott Taunton, managing director of UTV Media (GB), said: "UTV has backed Radioplayer since day one. Today's launch is just the beginning, and we look forward to working with our colleagues across the industry to explore where Radioplayer goes next."
A host of UK advertisers ran ad campaigns across the launch stations on the Radioplayer today, including insurance brands Direct Line and Swiftcover, and car manufacturers Volvo and Lexus.
Omnicom's Rocket and Albion have worked in partnership to create an online campaign that increases awareness of the Radioplayer from today by contextually targeting music lovers.
Radioplayer UK is a not for profit company founded by the BBC, Global Radio, GMG Radio, Absolute Radio and RadioCentre.