Town & Country Broadcasting is adopting a new brand as GCap has decided to retain the rights to the Xfm brand.
The new owner is currently conducting a period of test transmissions before the launch.
Xfm South Wales was launched by GCap Media six months ago, following the earlier launches of Xfm Manchester, Scotland and London. The station has been on the market since 11 February, when outgoing chief executive Fru Hazlitt announced plans to sell all three non-London Xfm stations.
However, once GCap's board accepted Global Radio's £375m takeover bid, the plans to sell Xfm Manchester and Xfm Scotland were cancelled.
A GCap spokesperson told Mediaweek.co.uk: "We sold Xfm at midday today and Town & Broadcasting became the owners with immediate effect. They were the main contenders since Xfm Wales has been on the market."
Martin Mumford, Town & Country Broadcasting's group managing director said: "This move represents a key strategic move for us, as we will be getting into the Cardiff market for the first time. We are currently in discussions with staff. The deal has gone through quickly, but we still need the opportunity to meet all the Xfm staff so we can decide how we will move forward."
Town and Country Broadcasting already operate Radio Pembrokeshire, Radio Carmarthenshire, Scarlet FM, Swansea Bay Radio and Bridge FM.