The rebrand plans will see Capital replace Global's six-strong pop music stations under the Galaxy stable, as well as the Red Dragon, Trent, RAM and Leicester Sound networks.
Starting from January next year, Capital will expand its reach to an audience of up to 47 million people on the FM band in Scotland, the South Coast, Birmingham, Manchester, Yorkshire and the North-East.
The new network of stations will share the Capital branding and be pitched as the "UK's No. 1 hit music station". However, the individual stations will retain their own breakfast and drivetime shows, as well as local news bulletins.
Under the changes, Cardiff-based Red Dragon will become Capital Wales, while Trent FM, RAM FM and Leicester Sound will combine to form Capital East Midlands.
The rebrand has been approved by media regulator Ofcom, as Capital and the Galaxy stations already share a similar music playlist.
Global Radio, which also operates Classic FM and London's LBC station, will hope to repeat the success of its recent merger of the Heart stations to form a new nationwide network.
Ashley Tabor, founder and chief executive of the Global Group, said that the rebrand will create a credible pop music alternative to BBC Radio 1.
"Capital will be the first proper national commercial competitor that Radio 1 has ever experienced," he told The Guardian.
"The Capital brand has a resonance not just in London but around the UK and internationally."
He added: "While we have had a lot of success with the Heart rebrand this is a different challenge and we have to make sure the name is correctly launched in each area.
"People know the Capital brand stands for quality and it can do things other brands can't do. We are the capital of hit music, that's how we view the brand. We are spending a lot of time and money to make sure we do it really well."