The Welshman will become the club's fourth summer signing subject to international clearance.
Doidge, 26, who has agreed a three-year contract, scored an impressive 66 goals in 122 games for Forest Green in English League 2.
Hibs said the player had been "tracked extensively by our recruitment team over a long period of time".
He will be given the Hibs No.9 jersey last worn by Jamie Maclaren.
Easter Road manager Paul Heckingbottom told the club's website: “We think Christian’s signing is a real statement of intent and I’m delighted we were able to fend off other interested clubs to secure his signature.
“The recruitment staff here have been looking at Christian for a while now and he’s also someone who was on my radar.
“We think he’s well suited to Scottish football, whether that’s leading the line or working with a partner.
“Christian is intelligent, has good movement, scores different types of goals, can handle himself physically and will press well from the front.
“He gives us something different up top.”
Doidge said: “I like getting after the ball with a high work-rate, making a nuisance of myself for defenders and playing off the shoulder. I like to attack crosses – just an all-round number nine, really.”
The forward joins Scott Allan, Joe Newell and Adam Jackson as new arrivals at Easter Road. The club are also understood to be closing in on a deal for Yeovil Town defender Tom James.