American-born Gambaccini, 48, was axed from Radio 3's Morning Collection show last September, less than a year after his arrival which triggered a barrage of protest.
He was brought in as part of a sweeping modernisation, but traditionalists complained that he was taking the station downmarket and expressed hostility to his accent and intimate presenting style.
The former Radio 1 presenter responded by branding them "the least civilised and most bigoted audience I have encountered in 25 years of broadcasting".
Gambaccini, who starts at Classic on 10 January, first worked for the station five years ago when it was launched.
Asked if he felt vindicated by Classic's decision to appoint him, Gambaccini said: "I do not think about Radio 3, it is behind me. There are lots of things to do in life and harbouring ill thoughts about something that happened two years ago seems to me to require therapy.
"Do I regret choosing a bad restaurant two years ago? No, of course not. I'm proud to be returning to Classic FM. Helping make it a success was one of the highlights of my career."
He will host Classic Countdown on Saturdays and, on Sundays, Countdown Top Ten, taking over from Nick Bailey.Reuse content