The move increases Xfm's audience by 10% to 836,000 listeners and means it will broadcast for the first time in Leicester, Norwich, Nottingham, Coventry, Cambridge, Bournemouth, the South West, and the M4 corridor.
All regions will hear the same DJs, including breakfast show host Lauren Laverne, who took over from Christian O'Connell when he left to join Virgin Radio.
But in the North East, South Coast and Midlands, locally relevant news, traffic, travel and events listings will be put together by producers in GCap's regional hubs.
The remaining non-London area multiplexes will receive a national service for the time being, but content will gradually be localised.
Xfm Scotland, launched earlier this month, has its own DJs and all content is produced in Glasgow. A similarly independent Manchester station is expected early this year.