It was confirmed last week that the country will be represented in Azerbaijan by veteran singer Engelbert Humperdinck.
> Eurovision: Is Engelbert Humperdinck the right choice?
> Ten Things About... Engelbert Humperdinck
Donovan told Heart FM: "Unofficially, I was asked this year to represent the UK at Eurovision. They actually came up to me and said would I be interested and I declined.
"Not because Eurovision is what it is, it's more about the fact that having just come off Strictly and feeling like I was under a bit of a microscope, I didn't really want to go through that experience again."
He added: "Also, it's such a big audience and there's such an incredible pressure.
"You get one chance; it's like being an athlete, really. You have to start at the blocks and then go. But it wasn't a tough decision for me."
Humperdinck has admitted to feeling "gobsmacked" by the reaction of the public to his appointment.
Donovan releases new album Sign Of Your Love this Monday, March 12.