GMG announced in December that it had agreed to purchase the Saga Radio stations for an undisclosed sum, but the acquisition was only formally completed this week.
A six-figure marketing spend will be invested in the rebranding as GMG repositions the Smooth stations to attract a more mature audience.
In December last year, media regulator Ofcom recently gave 102.2 Smooth FM in London the right to make a change to its format, allowing the station to focus much more on easy listening.
John Myers, chief executive of GMG Radio, said: "The Smooth name has worked well for us, especially in the North West where it has gone from worst to first in two years. We are therefore rolling this out across the UK into the Saga stations while dropping the 'FM' part of the name as it is clear that more listeners are tuning in across a number of platforms and not just on FM."
The new Saga licence for the North East, which GMG Radio will launch in the autumn, will also be named Smooth Radio.
Guardian Media Group acquired Saga Radio and its digital assets from Saga Group at the end of last year for an undisclosed sum.
GMG now owns 12 major FM stations, including its own Real and Smooth networks, and the Century FM stations in the North West and North East, which it acquired from GCap Media for £60m in October last year.If you have an opinion on this or any other issue raised on Brand Republic, join the debate in the .
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