At 10am, the new Capital network will start broadcasting on 95 - 106 FM as the "UK's No.1 Hit Music Station" in the biggest single expansion in British commercial radio history.
Under the relaunch plans, Capital will replace Global's six-strong pop music stations under the Galaxy stable, as well as the Red Dragon, Trent, RAM and Leicester Sound networks.
The new enlarged network is expected to reach an audience of around 6.5 million people every week across the UK, including listeners in Scotland, the North East, Yorkshire, Manchester, Birmingham, the East Midlands, South Wales, South Coast and London.
An advertising campaign for the station will launch today, featuring some of the world's biggest pop artists, such as Rihanna, Black Eyed Peas, Nicole Scherzinger and UK favourites JLS, showing their support for Capital FM.
Virgin Media will be Capital FM's first major sponsor, with commercials for the cable operator due to appear around the station's drivetime programme.
Global Radio, which also operates Classic FM and London's LBC station, said that the new Capital FM will broadcast the best in pop music, along with showbiz interviews, music events and news updates. It will directly compete with the BBC's Radio 1 as a national pop music network.
"This is a monumental day for British commercial radio, Capital FM, and Global," said Ashley Tabor, Global founder & executive president.
"The UK has never had a national commercial hits station before, this is game changing - another national brand, delivered locally, from Global Radio."
Richard Park, Global's director of broadcasting, added: "We are looking forward to bringing our new listeners across the country Capital's winning formula of the greatest, freshest tunes from the world's biggest artists."
Alongside the launch, Capital will also launch the Help A Capital Child campaign to raise funds for local children's charities. The initiative follows the Help A London Child campaign, which has raised more than £22 million since it started in 1975.