Classic Gold was acquired by GCap from UBC Media in April. It owns 18 AM and DAB stations, while GCap's own Capital Gold network comprises seven AM and DAB stations. All the stations are based in England and Wales.
Blackburn's last breakfast show for Classic Gold will be on Friday August 3, although GCap said it was in discussions with him about a series of new shows.
On the same day the on-air and online switchover to Gold will take place at 7pm, bringing in a single classic hits brand covering an approximate audience of 1.7m adults, accounting for 12m listening hours per week. This makes it the eighth-largest commercial national station based on reach, GCap claims.
Gold will target ABC1 35- to 54-year-old listeners, overseen by station director Andy Turner.
There will be four hours of daily afternoon local programming, with traffic, news and weather provided locally and news coverage increased to three minutes per hour.
Steve Orchard, group operations director of GCap Media, said: "The new Gold network will greatly appeal to authentic music fans and will reinvigorate the way classic hits radio is presented."
Blackburn's autobiography 'Poptastic' is coming out around September to coincide with the 40th anniversary of his broadcast of the first breakfast show on Radio 1.
Turner said: "Tony will remain on the GCap books and I look forward to working with him on a number of programmes to coincide with the launch of his autobiography."